Abbildungen der Seite
PDF
EPUB

LETTERS TO THE EDITOR.

[We do not hold ourselves responsible for the opinions
of our correspondents. The EDITOR respectfully
requests that all communications should be drawn
up as briefly as possible.]
**All communications should be addressed to the
EDITOR of the ENGLISH MECHANIC, 31, Tavistock-
street, Covent Garden, W.C.

I would have every one write what he knows, and this only, but in all other subjects: For such a person may have some particular knowledge and experience of the nature of such a person or such a fountain, that as to other things, knows no more than what everybody does, and yet to keep a clutter with this little pittance of his, will undertake to write the whole body of physicks: a vice from whence great inconveniences derive their original."-Montaigne's Essays.

as much as he knows, but no more; and that not in

DE OMNIBUS.

[47] SIR,-I may perhaps be permitted, under the above heading, to notice a few queries of a somewhat heterogeneous character, which would otherwise involve two or three separate short letters.

Imprimis: If Mr. Gould's "Ingenious Friend," to whom he refers on p. 378, were to take his gun down to the equator he would find that he might fire it either due east or due west without making any difference whatever, either in the range or flight of the ball, the earth and gun, pro illá vice, forming one system. On the other hand were he to fire it either north or south a theoretical deflection would undoubtedly take place. I much fear that it is the telescope of the "Optical Bricklayer" (same page) which is in fault; albeit, according to his showing it is by no means placed in a good situation for observing with. Still, imperfect discs to stars seem to indicate a defective figure to some extent in the speculum. With regard to Saturn he is of course very near the horizon, and unfavourably situated for observation; but your correspondent ought to see very considerably more detail than he appears to do with 7 and 5-16th inches of aperture. With your permission, sir, an engraving showing the precise aspect of the planet at present, in a perfect 4in. achromatic, will appear in these columns in the course of a week or two. This will enable the "Optical Bricklayer" to see how far his mirror fails in definition of this particular object. I am, of course, assuming that the eyepiece my querist employs has no defect in it; but at the same time 120 is far too low a power to use upon Saturn, and, for the matter of that, upon a star either, with such an aperture as he has.

STARCH.

it until more observations and experiments have been
carried out. Of course, as the grains are frequently
too small to observe the shape, with a magnifying
power of between 400 and 500 diameters, particulars
above alluded to refer to the larger grains. The mode
in which starch appears to be formed seems to bear
some analogy to crystallization-the definite point of
aggregation-the increase by deposition of material
on the outside-the cross shown under the action of
polarized light, all seem to bear this out. The last
point I will refer to is prevalence of starchy matter in
the air. On examining water under the microscope
that has been exposed to the air for a short time, you
rarely fail to find bodies, appearing to the eye like
starch grains, and, on adding iodine solution, these
grains give the characteristic starch blue. These
grains are so prevalent, that it is difficult to obtain
water without them, at least I have found it so.
the World of Science for July 27, 1867, there is an
article headed "Experiments with the Microscope on
the Effects of Prussic Acid on the Animal Economy,"
being a paper by T. Shearman Ralph, read before the
Medical Society of Victoria, from which I will make a
few quotations, leaving the readers to judge its bearing
upon the subject in hand, not presuming to express
any opinion myself. He says, "If the ordinary prussic
acid of Scheele be examined under the microscope,
under a power of 200 diameters, the acid, if pure,
will present nothing worthy of remark; but occa-
sionally specimens will be met with, which contain
Prussian blue, and also a number of starchy-
looking bodies, which actually turn purple with iodine

[ocr errors]

In

These

these changes will be found to take place in it, if the bottle is repeatedly opened and portions taken out ever so carefully." He goes on to say, remarkable changes appear to, me to be due to the renewed access of air, and minute particles of dust getting in, and to the possible electric state of the glass rod." He says if after a period of many days the bottle be shaken, and a drop placed on a slide, and examined with a microscope, bright blue particles will be seen

[ocr errors]

with a number of starchy-looking bodies, which polarize feebly and turn purple with iodine, like vegetable starch." "On taking a drop of prussic acid free from such contamination and some organic matter be added these starchy bodies will make their appearance. First of all a minute dot, resembling an oil globule, will be seen, which will be observed to increase in size, sometimes attaining to that of an ordinary starch grain and then it will assume a thicker consistence, and solidify into a starch grain," &c. The prevalence of starch in the air would account for its presence in the liquid. The last part of the quotation I must leave. Lastly, is it safe to rely solely upon the property of turning violet under the action of iodine, as a test for the presence of starch?

[ocr errors]

[48] SIR,- In the article on starch (page 162, No. 267, Vol. XI.) there are two little mistakes, "Inulien" should be Inulin; eleven lines from the end a full stop is inserted, where a comma only ought to have been placed-after "fennel; " this said, I proceed with the article from where I left off. 1st. The office performed by starch in nature.-Starch is the usual form in which nutriment is stored up for the future wants of plants or their offspring; the reservoirs in which this nutriment is stored are generally either the root, the seed, or, if perennial, frequently the stem. In the seed, All Cheques and Post Office Orders to be made pay and in such productions as the potato, the store is laid up able to J. PASSMORE EDWARDS. for the use of new individuals, in other cases for the future growth of the same individual. The starch grain appears to be attached to the side of the cell in which it is contained, and probably at the point or by the points called the hilum. It is difficult to distinguish the exact point of attachment, on account of the intervention of the cell wall; but by the difference of focus required to distinguish the two surfaces of the cell, it is easy to see whether a grain is contiguous to the floor or roof of the cell; if the attachment is by the hilum that point ought to be turned away from you when it is fixed to the floor, and towards you if fixed to the roof; as far as my observation goes this is always the case. If the grains were not attached, frequent movements might be expected to take place amongst them in the uninjured cells; but movement of the grains in these cells is the exception. The hilum of starch, like that of the seed, varies in appearance in the different kinds of starch; in the potato it appears as a point, generally more or less elevated above the surrounding surface. I have sometimes thought I could detect an appearance like a very small circle, the central portion, when viewed by transmitted light, not brighter than the surrounding. The hilum in wheat starch assumes various forms, such as a point, curved line, &c., and is at least generally even with the surrounding surface; in arrowroot it assumes frequently a fissured appearance, more or less depressed, the light being reflected from the sides. These instances may serve the present purpose. For the purpose of illustrating the formation and use of the starch grain, we cannot do better than follow the growth of the potato. The cells of the potato germ contain starch grains from their first development; during the early growth of the germ these are carried outwards in their containing cells, and may be seen in a thin section of the sprout. They are the first of the store consumed, and the difference in size between them and the grains in the body of the potato soon becomes evident. The vessels of the germ are distributed in the substance of the potato, similarly to the fibres of roots. The starch is contained in cells, the walls of which admit only of the passage of liquids; therefore, before it can serve as nutriment to the plant, it must be brought into a liquid state. With the growth of the plant, the size and number of the grains contained in the set diminishes until there are scarcely any left. The absorbable state is probably produced in a similar way to that in a germinating barley grain; that is, by the action of a special substance. But while starch is being assimilated, the production of starch is still going on. On making a section of the year's shoot of many plants, a number of minute particles are observed in the cells, and floating in the liquid on the slide, some of which turn blue under the action of iodine; in some, larger bodies are observed, which appear to the eye in all respects like starch grains, giving also the characteristic colour with iodine. This is the case with the potatoplant. A number of grains, generally more or less oval in form, are found, chiefly in cells surrounding the central portion of the shoot. As starch must become liquid before it can be absorbed by the vessels of the plant, these grains must have been formed in the cells in which they are found. The potato has not grown long before it begins to provide for future wants. It sends out side shoots underground called pendulums, the ends of which become enlarged, forming the potato. The sole function of the potato is to serve as a storehouse of nutrition for the buds developed on its surface, from the size of a pea to its full size; it consists of a number of cells containing starch grains, which appear to increase by successive deposits of the substance which composes them. The second special store is laid up in the seed, to supply nourishment for the in other words, that of the buffalo, ox, bison, and pig, development of the embryo. The starch grains is proportionately intermixed. At the extremity the serving this purpose are, at least generally, smaller epidermis, and occasionally minate portions of cuticle, than those stored up in the root or stem. In many adhere. The curling does not destroy the tendency to seeds a mass of cells exists surrounding the young generate ova. Wool and other material, from its plant analogous to the substance of the potato; in naturally oily nature, is also subject to the ravages of others the nutriment is only stored up in the seed neglected attention, alias moth, &c. Feathers ocleaves, which become, detached when the plant is in a casionally are subject to their attack, but in a much condition to procure sustenance from the earth, after less degree, inasmuch as these must be prepared by which the history of its internal economy is similar to some process before it is possible to use them. All the that of its parent. Light seems to be necessary for inferior materials used by the moderns cannot but the production of starch; potato-plants deprived of be the hot bed, so to say, of these destroyers, inastheir proper supply of light produce tubers which are much as old carpets in which they have long made deficient in starch, or are what are called watery-this their home, old clothing-in a word, the mixed refuseis the result of reading, not my own observation. The &c., contribute their quota to multiply them. And now green colouring-matter of leaves, called chlorophyll to speak of the more mystic causes-these will be for production of which light is indispensable--is some"If from the body's manifest upon unfolding facts. times produced in the same cells with starch, and it purity the mind derives a secret and sympathetic aid,” has struck me that the form of the two kinds of grain the homes of the wealthier portion of the community seem to bear some relation to each other. The grains should be subject to special vigilance in ascertaining of chlorophyll seem to be attached to the walls of their the condition of all bedding, and cause them to be subcontaining cells, and frequently to have a point on ject to a process capable of fulfilling all its intentions, their surface. Their chemical properties are of course and must be appreciable in an economical as well as sanivery different. In blanched leaves I have noticed the tary aspect. It will, of course, be readily conceded the cells are not empty, though deficient in chlorophyll, necessity of preserving the greatest immunity from all the little grains, showing the blue colour with iodine, cutaneous and febrile maladies, but others of a more The process occupy the cells, and appeared to me just as numerous. subtle nature demand equal attention. But, as this subject has only just come nnder my employed in manipulating is one simple and effective. notice, I must defer further expression of opinion on 1st. Thoroughly saturating with alkalies of a certain

Your "Subscriber" (4220), p. 382, will require the following lenses for the construction of the eyepieces he proposes to make:-1st for his 50-power, eye-lens, 53in; field-lens, 1.6in. Secondly, for the power of 100, eye-lens, 27in; field lens, Sin; and, thirdly, for that of 150, eye-lens 18in; and field-lens 53in. The practical detail asked for will all be found on p. 270 of the 5th vol. of the ENGLISH MECHANIC.

It might probably tend to obviate the difficulty under which "Gimel (4253), p. 383, labours, were the sentence which he quotes from Todhunter, transposed thus:-"The ratio of the circumference of a circle to its diameter is invariably denoted by the symbol." If he will read the words in this order, and then reflect that as the circumference of a circle contains the the diameter (8-1415926) times, it must contain the radius 2 times-and, quite obviously, that the semicircumference (180 or two right angles) must contain the radius half this number (or ) times-he will, I think, see that the two statements to which he refers are perfectly in accordance with each other.

π

Since I wrote the letter which you honoured me by printing on p. 369, I have received my copy of the current number of the Royal Astronomical Society's "Monthly Notices." I find that it contains an imperfect ephemeris of Winnecke's comet down to the 5th of this month, on which day its right ascension is given as 2h. 15m. 42s., and its north declination 1 59, Berlin mean midnight. It would thus be to the north of o (Mira) Ceti. It is travelling rapidly in a S.E. direction. But for the morning twilight it might be visible to the naked eye.

A propos of the reference you make to me (in your "Answers to Correspondents") in connection with the Astronomical Register I may say that I quite endorse what Mr. Proctor says, with regard to the value of its reports of the meetings of the Royal Astronomical Society, which are certainly unparalleled in any other serial; but that my chief complaint against it is the abominable dilatoriness with which it is published. Of all things on the face of the earth, it is essential that an Ephemeris should appear in advance of the time to which it refers; but my 66 Register never reaches me until the 3rd of the month, and has been much later. Considering the nature of its contents, this is quite indefensible, and naturally damages its already

limited circulation.

[ocr errors]

A FELLOW OF THE ROYAL ASTRONOMICAL SOCIETY. ERRATA.-On p. 369, col. 2, line 3 from the bottom, dele" but." In the next column on line 8, "It is printed for "He is;" and on the 11th line, "lapsis" for lapsus." Again on line 30, I find "object" put where I wrote "effect." Turning to col. 2 of p. 370, the word "brass," on line 25, is converted into "trap," and on line 81,"polish" appears for " "polisher."

Starch grains are considered frequently to form part of the contents of pollen grains; and certainly many of the particles forming the contents show the supposed characteristic colour with iodine. The pollen of the Ealla turns a deep purple-almost black-when touched with the iodine solution; the transparency and thinness of the skin allow the contents to be seen through; and yet I have never been able to detect starch in water in which pollen grains have been heated, whatever quantity I used of the pollen. J. C.

PURIFICATION OF FEATHERS, HAIR, ETC. [49] SIR,-The aphorism of the discovery of the circulation of the blood-"omne animal ex ovo"-is specially applicable to all the cognate facts (practically educed) from our present knowledge of the impurities of bedding and the mode of remedying its pernicious and wasteful effects,-pernicious because the conditions of health depend upon the adoption of that remedy, and wasteful, inasmuch as all materials, even though doctors disagree," are alike subject to the devourer moth, and the parasite. That their causes have their spring in the nature of the material we cannot deny; but nevertheless, the neglect of certain rules-viz., the submission of all material to the process under consideration-must inevitably eliminate and develop the ova in question. Horse-hair, so called, cannot where the markets are competitive be produced pure and simple

[ocr errors]
[blocks in formation]

strength. 2nd. Submitting the materials to sulphur | into A and project beyond, as B. Fit about 2in. of it dioxide in combination with water of a certain specific into A, so that, the dimensions of the square being 53in. gravity, so as not to destroy the material. 3rd. Well x 6 in. x 5in., there will be just 3in. projection of B steaming at a pressure of two atmospheres. 4th. outside of A (all the measurements are outside). C is of Removing to rotatory drying chambers, and finally to exactly the same construction as A, and has in addition the dusting machine. By this process, feathers, hair, a front with a hole for the lens. With the above you wool, &c., acquire a freedom from impurities, also obtain from 6in. to 9in. focus. C is fixed to the bottom elastic properties, and an intrinsic value not to be ob- board D. D has a groove or rather slit through the tained by other means. R. F. G. centre for the screw and nut E to work in, in order that the back A may slide in and out of C as far as you like, the screw and nut E tightening it when required. A works in a kind of shute formed by the pieces F F. Now in the sides of A and in the bottom there must be grooves for the focussing screen G of Fig. 1 and Fig. 2 to work in. At the bottom is a hole on one side of the slit (that E works in), for the triangle to be fixed to, if one is used. If a table tripod is used, no hole is required.

BORING CYLINDERS.

[50] SIR,-I send a rough sketch of the method for boring cylinders, which I think will serve to give "Amateur Turner" a slight idea of how they are fixed to the saddle of lathe, and likewise the sort of tool generally used to effect a true and smooth cut. The first thing to do is to plane off the valve facing on cylinder that is in case the steam chest is not cast on. After planing the face, fix the cylinder on the saddle of lathe, as shown in the sketch, then firmly bolt the cylinder to the saddle, so as to keep it from moving in any direction during the process of boring; this being done, fix the boring bar between the centres of lathe, taking care to have the boring bar sufficiently long enough to allow the cylinder to pass over the tool, or else the cylinder would come in contact with the back head. The saddle of lathe would be self-acting, so that when the saddle moved, the cylinder would move with it. The cutter would be firmly fixed on cutter bar, so that the cylinder would form the feed to the cutter. This is only one of the many ways used in boring cylinders. Turners have various ways for boring cylinders, but in the case described, the bore of cylinder would be true to a nicety with the valve facing. But where the cylinder will not allow of being bolted to the saddle, pieces of planed iron are put under the valve facing to keep it up to the required height. The tool shown is one that will effect a regular and true cut, owing to the number of cutters fixed on the edge of cutter boss. Some turners use more cutters than others for boring; in some cases there is only the bar, and one cutter fixed in a slot on the bar; but a true cut cannot be effected with this, for if the hole in cylinder should be cast a little out, there would be more metal to cat one side than the other; the consequence would be that when the cutter came around to take a deep cut one side and a light one the other, it would spring the bar, or press the cylinder over; whereas, in the other case, all the cutters would be cutting at one time, so that one or other of the cutters would always be in the deep cut, and keep the cutter bar, likewise the cylinder, from moving. In the course of a few publications, I will send a sketch showing how cylinder covers are turned on both sides, without any holes through them.

J. C. MOLLONY, Exeter.

[merged small][subsumed][ocr errors][merged small][subsumed][subsumed]

Fig. 2 is the dark slide or back. A is a shutter that runs in a light-tight groove. B is a hinged door, also light-tight. It is almost impossible to describe the making of Fig. 2. "Snatch Block" would do better to ask some photographer to let him see one. It is the most difficult thing in the whole apparatus to make. The cost of them is from 15s. upwards, from a manufacturer. C in Fig. 2 is a loop of leather to open B with. G of Fig. 1 is only some finely ground French glass fixed in a frame. I must impress upon the mind of the maker the absolute necessity of having the ground glass exactly the distance from the lens that the prepared plate will be when in the back. Without that the whole is useless.

Fig. 3 is a table stand. A is a flat piece of wood attached to B, which is a rod that runs in a hole in the blocks C and D. The handle E keeps it from slipping, so that it can be placed at any required height.

I fear that my description is not very clear, but as clear as I can make it, it being a very difficult thing, unless the maker is used a little to joining.

Let us hope that any one trying it may succeed; and that the tools may be in good order, and the wood not warp, is the sincere wish of Mus.

ELECTRICITY. - REACTION OF CURRENTS.

AIR-PUMP.

[52] SIR, -Without going particularly into the subject mooted by "R. P. S.," p. 875, for which I have not time at present, I may say that he is correct in his supposition, because it is well known that if several currents are acting on a magnet, it will take the direction which is the resultant of the several actions. Of course not only the direction but the force of the current also must be considered, the position taken being due to the combined actions and calculable from that which each of the currents acting singly would produce, hence it is not possible to draw such a figure as he does without taking the relative forces of the currents into account and also the resistance offered by the magnet itself.

I did not reply to "Induetorium's" earlier questions on the air-pump because he expressly limited the replies t.. the result of actual experiment on the same subject, but as he now takes a different position I may be able to help him. If I am not mistaken he will find

light Spanish is the best), or he may have it in more than one piece. Forplate camera:-Dovetail four pieces together. as A. Fig. 1, of in. thick, 7in. by Gin. x 3in. Next dove ail a similar square, only smaller, so that it may fit

the Sprengel's mercury pump serviceable, but the Groves's, as to which he enquires is very simple and efficient, but requires first class work; its principle lies in making the end of the barrel conical, and the piston also conical and fitting close to the barrel-end; there

is thus no space left in the barrel to hold air; when the piston is drawn back the barrel and receiver are in connection and come to equal pressure. The piston, es soon as it passes, closes the connection and compresses the air in the barrel, but does not depend for its expulsion on this compression rising beyond that of the outer air and lifting the valve; but even thus it seems to me that no possible exactness can prevent a little air following the piston on its return. For my own part I like the Tate's pump best of any I have tried, as I find that it exhausts very closely and with much less labour than any of the ordinary pumps.

The battery described by Mr. Conisbee is the Callan or Maynooth Battery which I have referred to, and quite agree with Mr. Conisbee as to its demerits, for which its cheapness at first is a very poor compensation indeed; but the cell enquired for was the Calland, a French device, and from the description evidently one of the numerous modifications of the Daniel.

[graphic]
[blocks in formation]

R is a small glass retort.

R

T T, a glass tube, graduated into inches and tenths.

coloured with aniline. V, a vessel containing mixture of alcohol and water

B B, a stout piece of card, 8in. x 10in., fastened to wall. A A A, a circular card, revolving on an axis, and carrying with it the pointer, a.

ddd, a circle inscribed on B B, and graduated into inches and tenths.

ccc, a larger circle, graduated (after trial) into barometric inches, &c.

Now fill V with mixture as above.

TT (which must be at least 20in. long) is now fitted air-tight with wax, into the neck of R. When hard heat R gently over lamp to expand the air therein, and immediately plunge bottom of tube T T into liquid in V. The air cooling and contracting will draw up liquid to (say) 6in., when it ceases rising; observe thermometer (say) 54 Fahr. Now by turning A A A around till pointer a coincides with 6 on d d d, the barometer is indicated, and supposing it to stand at 30.5, set the same down on the outer circle, c c c. The liquid may rise only to lin. Then temp. 54° brought round shows 29-2. Again, temp. 58°, glass 2in. = 30 barometer. CORNUBIA.

[graphic]
[graphic]

SUN SPOTS.

[54] SIR,-I beg to forward a sketch of a remarkable sun-spot observed here on the 21st ult., with an equatorial, by Cooke, of 4in. aperture, power 200. When first seen, on June 19th, it was nearly central,

eye, 5; station point, 12ft. Ex. 4, Fig. 5, 1ft. to left of spectator draw a cube of 4ft. side.

Make point B 1ft. to left of line of direction; from B to A equal 4ft., and as the cube is on the PL, describe a square which will be the real size, and from the angles, A, B, C, D, draw lines to the CV, and from B draw a line to the D P1, which will cut off the length of the retiring side A E. Make E F parallel to A B, erect perpendiculars from these points, and the figure is complete, leaving the one to the right to the ingenuity of the student, it being the same size, but one side coming on the line of direction. Ex. 5, Fig. 6, is a pyramid of 2ft. side, its altitude being 7ft., the nearest side 2ft. to the right of spectator.

[graphic]
[blocks in formation]
[blocks in formation]

and formed the preceding spot of a large scattered group, which measured about 2′ 52" in length. At 10 a.m. on the last mentioned date, an isolated mass of light, intensely bright and of a crescent shape, was remarked on a nucleus. This was carefully watched at intervals during the day; at noon it was no longer isolated, but formed a "bridge" connecting adjacent sides of the umbra. At 5 p.m. there were no traces of it, the penumbra having encroached upon the place which it occupied during the early part of the day.

On June 21st the spot appeared as represented in the accompanying drawing. The cyclonic type of the penumbra is here evident.

After the 21st ult., the group showed unmistakable signs of closing up; on the 24th it disappeared at the limb.

An unusual feature in the spot, and indeed in most of the large spots observed during the present year, was the uneven colour of the nucleus, which was very far from being uniform, patches of every shade, from a comparatively light brown to an intense black, were remarked. On the 21st ult., less than half the area of the nucleus was black; the remainder was of various shades of brown interspersed with small black patches. It is noteworthy that on the 19th ult. the central portion of the nucleus was brown and the edges black, and there was no gradual shading off between the brown and the black, but a sudden transition from one tint to the other.

As the sun is just now an object of great interest to astronomical students, perhaps some of your numerous readers have noticed similar phenomena.

I have observed and drawn most of the large sunspots which have appeared during the past five or six years; but, until the present epoch of maximum solar activity, have generally found the umbra of large spots much more uniformly black than they now are.

Is this peculiarity connected in any way with the present comparative shallowness of the penumbræ as remarked by Mr. Lockyer? THOS. G. ELGER.

Bedford, July 6.

[blocks in formation]

In a cube, or any other right-angled object, having one of its faces parallel to the PP, the sides will vanish to the C of V, as stated in the last, and by rule.

As things in perspective do not appear less till they are beyond the picture plane, all measurements taken on the ground line are true and geometrical.

It must be remembered that man has not an unlimited field of vision right and left, unless he moves his head. The angle of vision is limited to 60°, and a spectator looking along the line of direction towards the C of V can only see to the right and to the left above and below that line 30°, or, in other words, 30 all round. Therefore, the line of direction is the axis of the cone of visual rays-the eyes of the spectator being the apex and the circular base being on the picture plane (see fig. 2), so that objects coming outside the circle become distorted, and to see more we must stand farther back. It is not necessary to draw the base of the cone in every drawing, but it must be borne in mind.

Sufficient theory has been given for the present: we will begin with the practical part, under the conditions adopted by the Science and Art Department examinations, some of whose second grade papers I intend to introduce. Let the scale be in. to the foot, making the picture line and horizon line 5ft. apart, the station point being 12ft. from the centre of vision.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]

Set off A 2ft. to right, and B 2ft. more. Run off lines from both to the CV, to cut off on the retiring line BC, 3 ft. from A. Run off to the P D2 to the right, and BC is the perspective length of AB; draw the line CD parallel to the P plane, and the figure is complete. On the left is another plane, 8 ft. square; but instead of being removed to one side, one edge, FG, is exactly in a line with the spectator. Set off FE 3ft. on the PL. From E run up to the C V; take a line from F to the PD1 to left. The intersection H is the point through which to draw the line to form the back edge of the

[blocks in formation]

Let the student now reverse the planes, putting the large one to the right and the small one to the left under the same conditions.

will call them pavements; that on the right begins 1ft. Ex. 3, Fig. 4, is a series of horizontal planes-we

[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors]

to the right. Set off from A 1ft. to the points 1, 2, 3, 4, each being 1ft. apart; from them run off to the CV. From 1 run off to P D2. Now the intersection on line 2 is 1ft. within the picture; 3 is 2ft., and on line 4 is 3ft. Rule horizontal lines through the intersections, and the pavement is complete. This is a very instructive exercise on horizontal planes. I leave the other to the skill of the reader, they being the same size, the second lot being 4ft. behind the other. the student cannot see this clearly, complete the first without regard to those behind, and from point 3 draw a line to the D P, which will cut off the required distance, and proceed as before. We will now leave the planes and commence with the solids. Scale, fin. 1ft.

=

If

The one to left is similar to the last, but is removed 2ft. into the picture. Find the bases, as in previous examples; at the intersection of the diagonals erect a perpendicular of an indefinite height; now set up intersection on the axis of the pyramid is the point to the true height at H, and vanish up to the CV; the which the sides may be drawn.

DP

FIG. 7.

CV

<. BFT X 3FT

P

Ex. 6, Fig. 7, is a box of which the dimensions are given, the lid being open 1ft. Produce a similar one. to left, and remove it 1ft. within the picture.J. W. BEDFORD.

ELLIPTICAL GEARING. [56] SIR,-I send a drawing of a pair of elliptical It is wheels made as they ought to be, but never are. troublesome to set the teeth out, as each side of every tooth should be of the form that would suit a circular wheel of that particular radius; also pricking the pitch off the pitch line (represented by a dotted line), makes the teeth come a little thinner on the side of the wheels than round the ends, which does not signify, as the same teeth must come into gear with each other at every revolution, and so you may set them out as thick or thin as you please. Also it is to be observed that if at one end of the wheel a tooth comes exactly on the centre line, as is the case in the drawing at A and B, then the number of teeth must be odd. If for any

[graphic]

reason an even number is required, then, at the ends, the side of a tooth must come on the centre line, as is the case with the tooth at C, and the wheels must be put on the shafts heads and tails together. There is no objection to making the tops and bottoms of the teeth square if preferred, and there is no necessity for any contrivance for keeping them in gear, which ordinary elliptical wheels do require. Proved.-J. K. P.

UNEQUAL STEAM PRESSURE. [57] SIR,-With your kind permission, I purpose replying to Mr. Wood, seriatim, on the above topic in Vol. X., No. 258, page 606, where I think he has treated

us to a somewhat elaborate but erroneous lecture on unequal steam pressure, when contrasted with the general opinion entertained by the most eminent engineers of this 19th century; for they one, and I may venture to say all, believe in equal steaming.

Mr. Wood, at the outset of his last letter, says that we may have unequal steam pressure by having one valve right and the other too late, and the engine would be working right then to all appearance.

Now I have examined Mr. Wood's theoretical diagrams, which I will now explain. No. 1 has got an average pressure of 171b. No. 2 has got an average pressure of nearly 131b., that is 4lb. more on one side of the piston than the other, yet Mr. Wood has pronounced this engine as running right to all appearance.

After that we have diagrams No. 3 and No. 4, represented as being taken after the valves had been altered fin. at the cross-head, and of course must be the improved ones. We have no account of any more work being added to the engine at this juncture, yet the engine is actually taking 61b. more steam on the piston at each half-stroke; whereas if he had obtained by the alteration a continuous and steady motion, he would have required less, consequent on the fact that he had dispensed with the back-lash, or jars in the machinery, produced by unequal steaming.

"Alexandra's" design is not novel. It is simply the tail-end of a short horizontal grand stuck upright. Harp sichords and upright grand pianos were made of similar form during, if not before, the eighteenth century-not to mention that the form, as figured, of the Clavicytherum, the oldest stringed instrument with keys of which we possess a representation, is very similar in design. About 1845 Mr. Mardon constructed a piano of similar form.

The Euphonicon pianoforte patented in 1841, by Steward, whose design for a grand lately appeared in the ENGLISH MECHANIC belongs to this class, but it has no external case. Its strings are exposed to the air like those of a harp, being supported on a very ornamental metal frame. To my taste the design does infinite credit to the patentee.

Personally, my perhaps uncultivated taste prefers the ordinary tall cabinet pianoforte, when its case is well designed, and all its parts duly proportioned, to either the Enphonicon, which, from the exposure c its strings to the atmosphere, must be very liable to ge out of tune, or the elegantly designed piano of Mardon. The whole generation, with the single exception of the upright oblique grand, which had two bent sides, have, to me, a lopsided character. But this is a mere matter of taste, and as, with some personal suffering, they tanght me at school a small smattering of Latin, I will say " De gustibus," &c.

However much increasing the length of the strings may improve the bass, it don't in the slightest degree improve the treble. Now, as I know very well how to make excellent basses with strings 8ft. 6in. long, though it is far easier to make yet better basses with strings 5ft. long, there is no inducement to make instruments taller at the bass than at the treble end. It is the improvement of the latter which is the great, if not the one thing needful.

With regard to what I somewhat presumptnonsly termed the harmonium of the future, I must plead that I am a mere suggestor. If " Alexandra" fancied she heard the familiar "ring" of the Blacksmith's anvil in my letter on "The Harmonium," 'tis no wonder after a friendly intercommunication of 22 years on this and kindred subjects; and I accept her imputation as, though an unintentional, yet agraceful compliment. I am not a harmonium maker. In regard to the manufacturers of those instruments, I bear a similar relation to what my old friend the "Harmonious Blacksmith "bears to the members of my own vocation, excepting that I trust I am rather less "crotchety than he is. But n'importe. I make him pay me for his crotchets at a far more liberal rate than the public pay for their crotchets, and quavers too, when they can purchase three of Beethoven's pianoforte sonatas for the ridiculously small sum of 18., or a whole set of 45 of the same composer's delightful waltzes at a similar price. W. T., Pianoforte Tuner and Repairer.

low and high pressure, would then give out a steady motive power. As the high pressure cylinder is to be 15in., it will be about 16 nominal horse-power. We will suppose that we get 4 times its nominal horse-power from it, which is pretty fair rating for compound engines-i.e. 64 horse-power indicated; steam being cut off at of the stroke. Mr. Wood should have told "Inquirer" where he must cut the steam off in the low pressure engine to obtain the same amount of equal force, as it is just as necessary to know the latter as it is the former, if he must secure equal straining, and that steady motive power which he says would be given out. Again, he must bear in mind that if the engines don't give out equal indicated horse-power, he cannot possibly get equal strains from the same unequal sources. In compound engines, the object of the engineers should be to divide the strains in the working materials in addition to working the steam up from a very high boiler pressure to the lowest one practicable in the low pressure cylinder. Therefore, if the engine was properly constructed, and full of simplicity in the original design, they would get more practical results out of the steam (with the same sized engine) than they would out of the single engine with the advantage of the strains being more equally diffused in the working materials; whereas in the single engine, or expanding If Mr. Wood cannot convey his thoughts to paper the steam in one cylinder, the whole power, as it were, without the use of diagrams, it would be much better if being concentrated at the extreme points of suspension, he would be more careful in filling them up properly, is sufficient to break it down in very many cases. We or otherwise put the proper scale to them. In No. 1 will just illustrate this case. Suppose we have got a figure, at the beginning, we have gin. representing pair of engines compounded, and we were getting five 14-5lb. A little higher up the figure we have fin. and times their nominal power out of each engine; that 9lb. marked. In No. 2, we have at the beginning would be ten times the nominal power for the single fin. 1-32nd and 18-5lb. marked. If Mr. Wood can read engine if you dispensed with one; so the engine we this scale by measuring it, I must say he's an expert, kept on working would have to be of very strong build as it is neither 1-10th, 1-20th, 1-30th, 1-40th, or 1-50th indeed to sustain the severe strains at the extreme scale; perhaps he knows what it is. According to Mr. points of suspension; the other portion of the stroke it Wood's items, we have in No. 1 figure, at the commence- would be running nearly without strains. Again, he ment of the stroke, the steam coming on very easy, a says the diagrams in No. 236, as stated before, are not pressure of 1441b; in No. 2 we have only 184lb. (one so good to form judgment from as those in No. 242, inlb. less) and 1-10th of the piston's stroke late, which asmuch as the back pressure is not marked on them. amounts to a severe shock at the extreme points of sus- I answer, the indicator has not failed to delineate pension. We will suppose this engine to have a in this case the back pressure in the original figures 50in. stroke, divided by 10, which gives in. the distance any more than it has in the figures in No. 242, only the the piston would have traversed down the cylinder originals have been taken with a much stronger spring before any steam could be admitted to support attached to the indicator piston, consequently they the piston's motion. In this case we have unequal have a much less scale. If, when the indicator is fixed steam pressure, amounting to 4lb. more on an average and the atmospheric line is made, then the form of underneath the piston than at the top side. We have the the figure-the division between the atmospheric line greatest prime mover applied at the proper time. On and the figure-is the back pressure in high pressure the other side we have the least prime mover, coupled engines. If the indicator does not mark the back with the evil of the piston being moved down the pressure, then the operator simply takes the form of the cylinder 5in., it making a partial stop at this point; there-figure and omits taking the atmospheric line. In that fore a portion of the least prime mover has to be ab- case the paper would be minus the back pressure, but sorbed at this portion of the stroke in obtaining that the originals have got both line and figure. Again, I regular speed and steady motion which has been lost by can't see what the back pressure has had to do with the unequal steaming and unequal application of the prime information Mr. Wood has imparted to "Inquirer" mover. Yet Mr. Wood has pronounced this engine to previous to this controversy; for not one jot of inforbe running all right. I would ask Mr. Wood why he nation has had any reference to that part of the figure was called in to alter this engine if it was all right. which he deems so difficult to understand. He says The proprietors would not call any one in tc alter that in my next (meaning this) instead of saying that BICYCLE RIDING-A SURGICAL OPINION AS their engine unless their suspicions had been aroused "Inquirer" must put in. of lap on his valve, I shall aufavourable to its proper working. As Mr. Wood perhaps say gin. or in. No; I shall not do that. What seems rather dull in apprehending the bad effects of does he mean by this assertion? Does he mean unequal steaming and unequal application of the prime because I have made a little mistake that I have mover, and confounding the good by real assumption of falsified myself? I think if Mr. Wood will just reflect the bad, I will just give another simple, but I hope it over this last assertion of his, he will discover that he will be an effective, illustration of this gigantic power has exceeded the bounds of justice and not done as he unequally applied, which Mr. Wood is now advocating. would like other correspondents to do unto him. Again, We will suppose half a dozen gentlemen to enter some he says that if I had had an extensive practice with engine-room when the engine is running. This should- laps and staffs, and the indicator, I should not call them be steady motion, which now presents itself to their guess work. view, is nothing more nor less than effects produced by a current of alternate causes. If the engineer, one amongst the six, can discover, by any instrument known, or by his own practical touches on the machinery, that these effects are unequal, he knows then that the alternate current of canses must be the same. When they have discovered that the visible effects are unequal, such as irregular motion, and jars in the machinery of any kind, the least scientific amongst the six will come to the conclusion all at once that, as the visible effects are unequal, the alternate current of canses must be also. Scientific mes never expect anything else as a rule, much less engineers. Again, when "Inquirer" put forth his query, the subject he sought, I believe, was equal steaming. Mr. Wood perhaps, venturing outside his own avocation, tried to supply him with the requisite information to obtain this end. After this he comes in the corresponding field advocating and supporting with the greatest tenacity of purpose unequal steaming, and in such a manner as to astonish every engineer I am acquainted with. Yet under these unfavourable circuinstances, an engine is said to be running all right. So according to Mr. Wood's version of the steam-engine, it will work right any way. He wants to know whether "Inquirer's" engine (high pressure) is doing three-fourths of the work; if so, he must differ from me. There is no doubt of that: he will differ, and very much too, on the whole. I never said they were getting this amount of power through it, but simply used that rather high figure to convert him (Mr. Wood) to the practice of equal steaming and equal straining, which is quite as necessary to be attended to as the former. Mr. Wood says that I seem to have an idea that the steam ought to be worked up in the high pressure engine cylinder. I have no such thought as that, and the lap I recommend would not work the steam up any more than what would remove the compression, and perhaps not that if they did not get an equal application of the prime mover (steam). But if the steam cannot be worked up effectually in the low pressure cylinder, it must be worked up in the high pressure. Again, he states that Inquirer's" high pressure cylinder should be 15in. diameter, and the steam kept on the piston of its stroke. The pair combined,

And so it seems from this assertion that improper language would have been more congenial to Mr. Wood's feeling than proper, for in this case had I used the singular term (lap) instead of the plural (laps) he would not have attacked me on this point. Again, if he knew anything about engineering shop rudiments (which it is very evident he does not recognize), his feelings would have revolted at an assertion of this sort, inasmuch as staffs and lines of the most exquisite nature, both in the drawing office and in the workshop, have for this last century in particular formed the base of all the engineering processes of our greatest progressing engineers. Must this greatest perhaps of all sciences be abolished at the instiga tion of one man, whose practice is so little in this direction that he has never been able to enjoy it-" no, never."

Again, as far as guess work is concerned, I never said that the use and practice of the indicator was guess work. It is of Mr. Wood's practice that I say if it does not remind ns of the words guess work, it certainly does not indicate any very fine engineering qualifications. Next week I shall enter into the use and practice of the indicator. EDWARD MALBON.

"ALEXANDRA'S" DESIGN FOR A SALEABLE

UPRIGHT PIANOFORTE.

DESIRED.

[59] SIR,-I am an experienced hospital and general surgeon, and not a bad anatomist. I believe that bicycle riding is less likely to produce hernia or rupture than running, leaping, rowing, or other violent exercises which cause tension of the abdominal muscles with full extension of the thighs upon the trunk. On the contrary, I believe that the position i bicycle riding is that least likely to produce the injury. This opinion is founded on the anatomy of the parts, and as a practical test I would invite communication from any person who may have become ruptured by bicycle riding.

The origin of the prejudice is that the old dandy. horse was highly calculated to cause the accident, but in its use the feet pushed the road at a point behind the vertical line of the body, and so the abdominal rings become most exposed to danger.

I am, in a small way, a bicycle rider, and encourage its use in moderation. I have frequently advised it for exercise and recreation for those engaged in office business with small salaries not affording a horse.

I could make my own bicycle much more useful, if popular prejudice did not still consider such an dignified for professional men. The proposed broad band round the waist, like the soldier's belt, tends to rupture. Ireland, July 11.

COUNTRY SURGEON.

THE HARMONIUM.-"J. C. P." AND "ALEX
ANDRA."

[60] SIR,-In reply to "J. C. P.," who requires in formation about the best forms of reed organs, I am sorry to say I have not much of that same to communi cate, but the little I have, he is quite welcome to. 1 may very probably put him on the track of additional may add, that the reference I make to patents, &c., information. Myers's patent, containing a specification [58.] SIR, I fear, so far from making that portion of the means of varying the pitches of reeds throughof the case of a piano which is above its keys of the out the entire compass of the instrument at once, is unusual, though not unprecedented, form which our No. 8164, price 1s. 10d. I have not much faith in the Princess proposes, it would render the instrument yet possibility of carrying this out in practice, because, more unsaleable than an ordinary cabinet 6ft. high, at from the difference in the lengths of the reeds in the least until it became fashionable; for anything in the bass and treble, and the fact that those differences in fashion, however it may sin against good taste, is cer- length are not the only means employed to produce the tain to become popular with her sex. I, for one, should required succession of sounds, I cannot conceive how be very sorry to make a set of four, or even a pair, on to make the compressers, which alter the vibrating speculation. Besides, I thought I had clearly ex-length of each reed in an Eolophon or harmonium, so plained in my last letter, that a man who understands that they shall raise or lower the pitch of each one reed his business-who does nothing without a why and a the required amount in relation to the others; but if wherefore-who don't trust to bellymen, i. e., sounding "J. C. P." procures and reads this and the other board makers and string coverers, to do as they authorities I shall refer to, he will cheaply acquire an please finds no difficulty in making a good bass to a amount of information which I could not communicate piano 4ft. high. without occupying a larger space in the ENGLISH

JULY 15, 1870.]

ENGLISH MECHANIC AND MIRROR OF SCIENCE.

MECHANIC than I should be justified in doing on a subject of not very general interest. Indeed I have lately occupied so much of that space on musical and other subjects, that I think it is quite time I exercised a wise discretion and occupied less of it with my many lucuI have not quite forgotten Mr. Spence's brations. designation of me as "the universal letter writer." Day and Mundies' patent, No. 5062, price 10d. (my own Eolophon is constructed on their system of air chambers or short pipes composed with free reeds). Wheatstone's patent, No. 10,041, price 28., describing a combination of reeds and air chambers in the form of stopped pipes placed a considerable distance above the free reeds, which, under these circumstances, induce powerful resonances in the masses of air contained in those pipes or air chambers, will afford him much practical information and food for thought. Yet more is contained in Wheatstone's patent, No. 10,041 price, 28. on what may, in contradistinction to free, be fairly termed string reeds; for although Wheatstone was not the first inventor of these (Professor Robison was;-see his Mechanical Philosophy edition of 1804), he was their great improver, for he showed how they could be made to utter not only the reed tones proper to them but also to cause the vibrations of a table d'harmonie, or true soundboard, and thereby compel it to utter its own sounds in unison with, and in addition to the reed tones. While on Wheatstone I have much pleasure in bearing testimony to the fulness and lucidity of his specifications: he leaves nothing to the reader's imagination, but makes, by his drawings and unusually clear descriptions, the matter plain to the "meanest" capacity-my own for instance.

May I presume to give "J. C. P." just one little bit of advice, and that is to endeavour to carry out our Princess Alexandra's idea, and make an harmonium which shall deserve-from the great variety of the timbre of its different ranks of reeds-the title of wind "organ?" Nothing palls like monotony. No doubt the harmonium of the future suggested by my friend "W. T." is not a small affair; but then his ideas are based on his familiarity with such instruments as the organ at the church of St. Sepulchre and similar anything-but-small instruments, but I think I can see pretty clearly that both he and the Princess are quite right in their demand for variety of timbre, so I should recommend "J. C. P." to go in for something like it, and provide bellows-Qy. more than one-large enough to enable him to add half a dozen ranks of reeds at any future time when he has tired of the familiar tone of his first loves.

Before commencing operations, let me earnestly entreat him carefully to examine the professional harmonium advertised in several Nos. of the ENGLISH MECHANIC, and probably deservedly commended by Mark Ellor; also the best productions of Alexander, Ramsden, Evans, and last but not least, of Herman Smith, who has afforded the readers of the ENGLISH MECHANIC SO large an amount of practical information -which I trust " J. C. P." has read-and who promises yet more, for which I hopefully and anxiously wait. I also recommend him to use every opportunity of picking up knowledge by reading and observation of the practice of the mastersof this art, on the principle of the wise precept, "in all thy gettings get knowledge." (N.B. If you can get money also, so much the better) too. For many years I have carried this precept out in the matter of "strynged" musical instruments, the pianoforte especially, but I am yet, notwithstanding a pretty extensive experience-very glad to avail myself of the practical experience and ability of my fellow correspondent "W. T." (By the way I see, "Alexandra" says, that when writing about his harmonium of the future, he signed "R. T.") to carry out my crotchets; for after all, we amateurs, however clever we may be, or rather think ourselves, at the thinking business, are usually poor hands at the practical.

THE HARMONIOUS BLACKSMITH.

66

THE MANICHORD-QUERY, WHAT IS IT? [61] SIR,-This instrument, and many of its predecessors, is figured in Rimbault's "History of the Pianoforte," and he thinks it was simply an extra long The manichord and superior kind of clavichord. ye mono chordis," must not be confounded with which seems to have been simply a name prevalent in Scotland and elsewhere for the clavichord. I have little doubt the manichord was a species of clavichord, differing from the ordinary instrument of that name in the construction of its tangents or string strikers. Probably there were two clavichords, the one with clothed tangents and the other with its tangents of uncovered metal. I strongly suspect the latter is the instrument whose name used to be written clarichord, from the French word clair (clear), for its tones would be much brighter than those of one whose tangents were clothed, even if only with vellum. The fact that no clavichord with clothed tangents has come down to our time is no proof that such never existed, for their clothing may in the course of perhaps centuries have perished, just as the clothing of the action of the piano often does in a few years, with the assistance of

moth.

Although I have not seen an ancient clavichord with clothing on its tangents, I have seen a modern one. About two years ago one of this kind, of German make, which belonged to the late Mr. Prowse, was sold I traced it to the by Messrs. Puttick & Simpson. possession of the bandmaster of the Royal Artillery, but could not recover it. I suspect this is properly a modern manichord, and that by simply taking the leather coverings off its tangents, it would cease to be one, and become a clarichord.

THE HARMONIOUS BLACKSMITH.

THE EARLIEST OF PIANOFORTES.

[62] SIR, Considering that the keyboard was em-
ployed to open the valves or pallets which admit air to
organ-pipes at least as early as the ninth century, it seems
rather improbable that the same contrivance (probably
reduced in width to suit the fingers instead of the
"organ-beater,"
the never-to-be-forgotten
fists of
whose descendants are far from extinct until this day)
was not employed to put in motion the strings of
musical instruments designed on the model of the harp
or the cythera. At a period of probably a thousand
years ago it is quite likely that this was done in those
eastern countries in which the pipe and free reed
organs have been known in a more or less complex
are acquainted with. Our ignorance of such records is
form from a period anterior to any historic records we
at best only negative evidence of their non-existence,
or that stringed musical instruments, sounded by
manuals, had not been constructed-an assumption
based on the too common fallacy of making our igno-
rance a measure of possibilities. As well might it have
been assumed that America did not exist, because
centuries elapsed before Columbus re-discovered that
division of the earth; and, as the knowledge of its
existence had died out, a geologist of the period, with
that turn for hypothetical speculation, if not for logical
deduction, which distinguished the predecessors of
Lyell, might have learnedly proved (to his own satis-
faction at least) that (like Venus anno domini) what
used to be termed the fourth quarter of the world had
that early period been sufficiently developed to enable
just risen from the sea. N.B.-Mathematics had not at
us, by a very different kind of calculation to that deno-
minated the differential calculus, to "kalkalate" that
Australia was a fifth quarter of the globe. It would be
well for us if our astute Chancellor of the Exchequer
could, by a similar "kalkalation," repeatedly convert
four quarters' taxes into five, for then a handsome
surplus would be the normal condition of revenue, and
we might hope John Bright's summum bonum of
earthly happiness, "a free breakfast-table," might
carnal things.
soon be realized. Verily our stout Quaker thinketh of

The earliest keyed musical instrument with strings
of which we have any record is the keyed cythera or
clavicytherum; and its earliest known representation
exhibits it standing upright, just as if some clever
fellow of the period did what was afterwards patented
fortunately the patent rolls of that early time, when
in England about 1800-viz., put keys to a harp. Un-
clavicythera were made for love or money, have not
been found either in that receptacle for unseen antiqui-
ties, the British Museum, or anywhere else that I am
aware of; so I cannot at present determine the interest-
(by the
ing question, whether King Nebuchadnezzar, when
tired of the cares of state, set us the first recorded
example of "monarchs retired from business"
way, I fear Dr. Doran forgot him), and wisely recruited
his exhausted energies by a diet "intirely vegitable,"
as those innocent advertisements of vegetable rank
poisons express it-I was saying that whether he,
under the circumstances of his forced residence in the
to grass" for the season), solaced himself with his
country (I mean when like my horse he was "put out
clavicytherum as Queen Elizabeth said she did with
her virginal (I fear in her case female vanity had
something to do with it), we have unfortunately no
means of ascertaining; for the writings of the harmo-
nious blacksmith of that early period have (if ever
they existed, I have not seen them) as certainly
perished as those of the somewhat garrulous person who
had that title imposed on him in early life will do
when something better is written (N.B.-Doing this
would be far from difficult) to more worthily occupy the
In the clavicytherum the strings were treated like
place in our journal which his writings don't deserve.
those of the harp, the lute, the guitar, and modern
unsuccessful students are "until this day"-i. e., they
were plucked. I only hope the latter, who are not in-
variably saints, utter as sweet sounds when they under-
go (for their good) this very needful process, as the
musical instruments enumerated do, and that the said
students don't become "instruments of wrath," or
ever utter sounds associated with the idea of "con-
demnation." When the clavicytherum was laid on its
side it became the spinet, and when the spinet was put
into a rectangular case it became the virginal. Both
gradually developed into the harpsichord, certainly the
king of its class; but perhaps I am a partial judge,
and I confess to a weakness for one of my early loves.
It is not needful I should describe so comparatively
well-known an instrument here, for I have done so
at pretty considerable-perhaps rather too great-length
in my appeal for the earthly salvation of ancient musical
innocents from the Herod-like destruction they undergo
from the modern Goths and Vandals, who work their
wicked will on them, to the great sorrow of collectors,
who would be willing to pay almost any ransom to
rescue them from their captivity among those barbarians.
The whole generation of harpsichords, spinets, &c.,
whose strings are plucked by plectra not held in the
The
hand, or by the finger itself, were deficient of the
power of expression, until other means of causing the
vibrations of these strings was resorted to.
example of the various harmonicas, as for instance,
that formed of pieces of wood (probably the most
ancient of all), which has risen from the dead with a
new Greck name, Xylophone (N.B. It has very little
" in the musical sense, and its sounds have a
"phone
strong family likeness to those elicited when Punch's
wooden cudgel comes in contact with the almost
humanly wooden head of another puppet-it is far
inferior to the old wooden harmonica in the East India
Museum) and yet more that stringed harmonica the
santir, which we call dulcimer, naturally led to the

pro

substitution of a hammer for a plectrum, and this
duced the first "forte piano," with keys, for, in truth,
all the harps, lntes, cytheras, and dulcimers, were true
pianofortes in the musical sense-i. e., they were
capable of expression, and, therefore, piano fortes in
the musical sense of those words.

The earliest pianoforte with keys of which we know
any examples is termed the clavichord, probably from
clavis, a key, and chorda, a string. I have before fully
described this instrument, so I refrain from vain repe-
tition. Whether the hammer which strikes the string
be rigidly fixed in the key or detached from it, so long
as it is a hammer, it enables the performer to vary the
hammer instruments are true "forte pianos."
loudness of the sounds-i. e., to play with expression,
which a plectrum moved by a key does not, hence all

It is by no means certain that, although the earliest now known, the clavichord was the earliest of hammer instruments; it is at least probable that some action more resembling that of the drumstick, or the striker held in the hand of the dulcimer player, preceded the tangent. Making the striker or hammer perform the was compelled to lift up his striker immediately after function of a bridge rather seems a refinement which could hardly occur to a performer on the dulcimer who is a gross error, they he had struck the string with it, or he would have produced the effect termed blocking by pianoforte makers. Perhaps on the principle that all discoveries are said to be accidents-which, by the way, are far oftener the result of profound thought and careful experiment-the tangent of the dulcimer may "soft body," if sympathy for the thing I hope I never may become, I prefer being have been suggested by the falling of a hard body (a. sneered at as a suffering of others deserves that title) across the string, and at once putting it into vibration and, by shortening its vibrating portion, raising its pitch. It did not require a remarkably clever artist to transfer this effect by employing a striker-i. e., the tangent, fixed in the key. I think (although but a "soft body ") I could have done nearly as much myself; but end ready for you. Many great reputations are very then it is so extremely easy to set the egg upright when some one-too often utterly forgotten-has broken its cheaply made in this way; but man has a perverse proclivity to set up idols and shams for worship.

The earliest hammer harpsichords or pianofortes, in the modern technical sense of the word, of which any known record exists, are those made by Christofali, of described, and their action figured, in the "Giornale Padua, in or before 1701. In these (which are fully de' Litterati d'Italia," A.D. 1711) the hammer acts like a drumstick, or the striker employed to vibrate the strings of the dulcimer-i. e., they rotate on a hinge or centre. So, in the modern technical sense, Christofali makers, yclept Christofali, was before his time; for he was the first pianoforte maker on record. It is remarkable how far this early Christian father of pianoforte especially says that this kind of harpsichord ought to have much thicker strings than those of the ordinary sort. He also anticipated some of the most supposed comparatively modern important improvements in the action, especially the escapement of the hopper or acute-angled receptacle, thus preventing it from rehammer lifter, and allowing the hammer to fall into an bounding to the string by a contrivance which is in principle the same as that afterwards re-invented by Robert Stodart, and patented under the name of the check.

This ex

I have already said that to produce a true forte piano, in the musical sense, the hammer need not be detached from the key. Neither is it absolutely essential that it should rotate on a hinge or centre: in a word it clavichord were guided by two sockets, similar to those need not, except as a matter of practical convenience, be a lever. It is obvious that if the tangent of the which guide the damper wire-stickers of a piano, and its edge kept at a right angle with the string, it would act even better than it does when fixed in the key; for then its path is not quite rectangular, but really a circular arc whose centre is the key balance. Like such a tangent, a sticker, whose top surface might be strike the string; and if the key were prevented by a of wood, either clothed with leather or felt, or not clothed at all, similarly guided, could be employed to back touch or otherwise from lifting the supposed sticker with rectangular motion quite up to the string, its path would be completed by its momentum-it would strike and rebound from the string. tremely simple action was not I believe evolved out of the depths of my consciousness, as Kant would have expressed it; but, if I am not mistaken, it was actually used by Marius, in one of his three claviciens à mallet A.D. 1716. It seems to be the rule "in that case made and provided," that old things shall be reinvented and letters patent obtained for them. This not very valuable invention, in a practical sense, was no exception to that good old rule; for, in 1787, Master It does, indeed, seem a strange way of Humphry Walton (not him of the clock) patented a combination of it with the ordinary hinged or centred hammers. The much older plan of hitting striking the strings of a piano to do it by means of ordinary hammers. punches-for this is just what Walton's perpendicular hammers are which panches are themselves struck by severe on poor Walton: perhaps he was actuated by the the strings with the hammers themselves seems at once simpler and more effective, but we must not be too best of motives; and, as he was prevented from using the check by R. Stodart's then existing patent right, he benevolently devoted his ingenuity to contrive something producing the same result as Stodart's invention, not within the purview of his patent, which might afford the musical public similar advantages without that public being wholly dependent on Robert Stodart. Nevertheless, Master Walton seems to have

« ZurückWeiter »