DISINFECTANT FOR SCARLET FEVER. AF. F. C. says, "I much regret that in writing about my homely, but apparently most useful,method has been coinmunicated to us (Food Journal) for disinfecting houses and rooms in which cases of scarlet fever have occurred. Dissolve saltpetre up to the point of saturation, and in the solution soak several sheets of coarse blotting paper, which must be allowed to take up as much as they can, and be afterwards dried. Carefully close every door, window, and chimney of the affected room, and let the prepared blotting paper be lighted and smoulder itself out. This is of course not intended to supersede the use of Condy's fluid, the value of which in every household where there is sickness is sufficiently well known; but we have heard of such success in checking the spread of infection by means of the saturated paper, and it is moreover so easy of trial, that we gladly publish the in

formation sent to us.

LEX, who does not send his address, is mightily offended
because we did not insert his answer to "R. P.," whom
he charged with "deliberate equivocation" and "gross
ignorance," and like a petulant child who breaks the
toy he does not understand, he ceases to be a sub-
scriber. He says "the loss you have sustained by not
publishing my letter is small (five subscribers), but if
other letters are similarly treated you will ultimately
awaken to a sense, &c." We shall continue to trest
absolutely discourteous correspondents in the same
manner, if we lose five or five thousand subscribers.
as we know very well that we should get 10,000 more
subscribers in their place.
F. JORDAN.-A puff nevertheless.
A. M. KEAYS.-We can't say. Have nothing to do with
doctors who advertise questionable works.
J. R. M.-See Needham's "Starter for Sewing Ms-
chines," p. 232, this volume.
J. R. K. The number was sent. We cannot be respon
sible for Post-office losses or irregularities.
J. M.-The query appeared and was answered.

laying down of a galvanized iron speaking or whisper. foundation of her shipping and carrying trade. It was, T. W.-Crocus is the commercial name of a polishing

THE ADVANTAGES OF SCIENCE.-Chemistry, therefore, in its highest, and, it may be said, its most theoretical investigations, is most justly to be cultivated by a nation. In an ordinary sense the resources of a nation lie in the growth of its soil, as well as in the minerals which the soil contains, and likewise in the fish of its rivers and of its seas. Holland, limited in its soil, and destitute of minerals, sought in fisheries and in whaling other materials for wealth, which have been the however, by the applications of science that Holland, in a less progressive age than this, endowed herself with further resources and constant employment for her population. By a better application of politico-economical doctrines she enlisted skilled labour; favouring the persecuted, she attracted capital; protecting the Jews, she raised her public and private credit as an assured means of providing herself with wealth. Holland, by free trade in corn, was the entrepôt of Europe, and became the great money market. By the prosecution of chemical and mechanical studies, then favourably fostered by the possession of the great book and publishing market, Holland promoted every branch of manufacture, acquiring a supremacy over the world in many departments. If Holland has no longer the monopoly of these advantages, it is because the late war fell heavily upon her; and that other powerful nations, particularly our own, are engaged in the same career, leaving Holland only a minor share.-Food Journal.

The English Mechanic

AND

Having stated these premises, let us proceed to
the consideration of the square. The square is a
rectangle having all its sides equal, and its area
is found (commonly) by squaring one of its sides.
Taking the square A B C D (Fig. 1), it is evident
that if we multiply two
FIG.l

MIRROR OF SCIENCE AND ART. of its sides.

FRIDAY, SEPTEMBER 16, 1870.

RECIPROCAL GEOMETRY.

By J. BEVERLEY FENBY, C.E., M.I.M.E.

T very frequently happens that those who have

say A B
D
x B C, we shall get the
area, just as we should
by squaring any one
side; and, in fact, the
rule for squaring one
side arises merely be-
cause all the sides are
equal. That this is

the case is evident when A

с

B

we come to consider the oblong or rectangle

circle is to the ellipsis, as regards area; and to
calculate these FOUR figures it is only necessary
to remember Two facts, namely, the multiplica-
tion of two adjacent sides-
3-or the diameters at
right angles-and the factor 7854. If, therefore,
the student will impress these simple reciprocal
relations upon his memory he will perfectly
master four very useful facts in practical geo-
metry.

Passing from the consideration of these four
plane figures to that of the solids derived from
them, we find the same beautiful laws of geome-
trical reciprocity to hold good. From the square
is derived the cube, and its solid contents are found
by cubing one of its
sides. For our pre-
sent purpose we will

I ve make geometrical calculations for practical A B CD, Fig. 2., for here we must take two ad consider the cube on

D

A

FIG. 2

a

A

FIG. 4

D

purposes are at a loss for the proper formula for
some particular case, and are therefore under the
necessity of referring to a pocket-book for some-
thing which they require. No matter how reten-
tive the memory of any engineer, or how
thorough his training, it is impossible for him to
carry all necessary formulæ in readiness by
memory alone, hence the need of some form of
pocket-book. In many cases, however, there is
some reciprocal relation existing between that
which he has "at his fingers' ends" and that
which he does not at the time remember, which
would, if known, obviate all doubt. Some time jacent sides, as A B, B C, though the oblong
back, a draughtsman employed under the writer differs only from the square in having its opposite
had to deal with a problem in the designing of sides equal to each other, but wanting the equa-
some machinery, involving the calculation of the lity of the whole four. If now we take the case
cubic contents of a spheroid. As to the proper of a circle-inscribed for the sake of illustration
mode of performing this calculation, the draughts- in a square-we find that the area is obtained by
man-though a very well informed, and withal multiplying the two diameters of A B and C D
industrious youth-was evidently at sea, for, after together (Fig. 3.), by which we obtain the area
looking for some book, which he failed to find, he of the circumscribing
applied to the writer for the requsite formula.
square, and then re-
FIG. 3
Inquiry elicited the fact that he was perfectly ducing the product by
well informed as to the method of finding the con-
multiplying by the
tents of a sphere, and also that he had on more factor 7854; which in
than one occasion worked out the problem as re-
effect reduces the area
garded the spheroid, but without noticing any
of the square a b c d
special relation between the two. The writer of by the sum of the parts
this memoir, in place of giving him the formula A a C, Cb B, Bd D,
for the spheroid as an isolated one, gave
and D c A, the excess
him a comparison between the contents of the of the square over
cube, parallelopipedon, sphere, and spheroid. the circle. Inasmuch e
With these relations he seemed much struck, and as the two diameters A B and C D are equal,
expressed his surprise that such reciprocity in this rule is commonly given as though only
geometry was not pointed out in every work on
one diameter were multiplied by itself or squared.
the subject. Further researches on this subject The consideration of the ellipsis will render this
brought to light the fact that not only were self-evident. To find the area of the ellipsis in
standard treatises silent on the subject, but that Fig. 4. the diameter A B is multiplied by the
very well-known men actually, at first sight,
denied that the alleged reciprocity existed. The
fact that men accustomed to performing calcula-
lations had, in so many cases, missed the very
beautiful principle of reciprocation which runs
through geometry naturally aroused the writer's
attention, and led to the compilation of the fol-
lowing notes on the subject. Before commencing
to explain the reciprocations hereafter stated, it
may be well to state that it is not supposed that any
original discovery is here embodied, but merely that
practical men have overlooked a fact that would
materially lessen the labour of calculation, as diameter C D-by which we obtain the area of
applied to geometrical figures, such as constantly the oblong a b c d-and this area is reduced by
crop up in practice. It must, therefore, be clearly multiplying by the factor 7854, so as to deduct the
borne in mind that this little memoir is intended sum of the parts A a C, Cb B, Bd D, and D c A;
solely to aid practical men in performing calcula- that is the excess of the area of the rectangle
tions, and not as an exercise for mathematicians. over that of the ellipsis.
The geometrical figures to be treated of are (1)
the square; (2), the oblong; (3), the circle; (4),
the ellipsis; and the solids directly derived from
them-namely (5), the cube; (6), the parallelo-
pipedon; (7), the sphere; and (S), the spheroid;
and the object aimed at is to show how the mode
of calculating each of these figures is reciprocally
related to all the others, and thence to prove that
it is easier to remember them as a group very
closely related than to take them disjointedly, as
is done in the ordinary text-books. To the pro-
posed mode of consideration, it may be objected
that the eight figures enumerated belong to three
branches of geometrical science, namely 'plane
geometry, the geometry of solids, and conic sec-
tions. As an abstract question, this is un-
doubtedly true; but in practice these three
branches are promiscuously mixed; and, as we
only propose to deal practically with them, we
think no valid objection exists to treating them
in their reciprocal relations; the more so as a just
comprehension of their affinity to each other will
very materially help the student in understanding
their properties and, therefore, in appreciating
each in its justi e ⚫he three great branches

If the reader has carefully followed the cases given he will easily perceive that we have shown that the area of the square and that of the rectangle are found by identically the same process, namely, by multiplying two adjacent sides together. He will also perceive that the area of a square circumscribing a circle is first calculated to obtain the superficial contents of the circle, and that the latter area is simply 7854 of the former.

Further, it is observable that the area of an ellipsis is deduced from that of the circumscribing rectangle by multiplying by the factor .7854. The results, then, which we have arrived at may be stated as follows:-FIRST. The area of the square and that of the oblong are obtained by identically the same process, namely, the multiplication together of two adjacent sides; the squaring of one side in the case of the SQUARE being an accidental consequence of the equality of all its sides, and in no way affecting its properperties as a rectangle. SECONDLY. The area of the circle is deduced from that of the square, and the area of the ellipsis from that of the rectangle, simply multiplying by the same factor, namely, 7854. Hence the square is to the oblong as the

evidently the solid contents of the circumscribing cube, and the multiplication is equivalent to the process of cubing the diameter of the sphere on the side of the cube. The excess of the contents of the cube over those of the sphere is reduced by multiplying by the factor 5236, which practically turns off the corners of the cube. Extending the analogous processes to the next case, that of the spheroid, we find precisely the same rule holding good. To find the solid contents of the spheroid, A B C D, Fig. 8, the ordinary rule is to multiply the stationary diameter A B by the square of the revolving diameter C D, and then by the factor 5236. This is equivalent to multiply. ing the stationary diameter A B by the two diameters CD and E F; the latter being

N

right angles to each other. This process gives us the contents of the parallelopipedon ab e deƒg, and the reduction of this by the factor 5236 nsed as a multiplier gives the contents of the enclosed spheroid. In Fig. 8, a prolate spheroid is shown, but the principle holds just the same with the oblate spheroid.

The relations we have traced may be thus summarized:

Firstly. Consider the square and the oblong merely as rectangles, and for the area multiply two adjacent sides together (these two being equal in the square).

Secondly. Remember the factor 7854, and for circle or ellipsis multiply two diameters at right angles (observing that these are equal in the circle, and that the major and minor are to be taken in the ellipsis); the area-which is that of the circumscribing rectangle-will, when multiplied by the factor, give that of the circle or ellipsis, as the case may be.

These two cases embrace the four plane figures of which we are treating-namely, the SQUARE, OBLONG, CIRCLE, and ELLIPSIS.

Thirdly. To find the solid contents of any cube or parallelopipèdon multiply any three sides which give the length, breadth and thickness, and the product will give the result required.

The CUBE only differs from other PARALLELLOPIPEDONS in having ALL its sides equal.

Fourthly. Remember the factor 5236, and, for the solid contents of the sphere or spheroid, multiply three diameters together; observing that in the sphere all these are equal, while in the spheroid two only are equal, and these are of neces

sity revolving diameters. This multiplication gives the contents of the circumscribing cube or parallelopipedon, and the reduction of the result by the factor 5236 used as a multiplier will give the contents of the sphere or spheroid.

came to my mind."* From these low hills on and a larger pair i and k on the E. part of the
the N., and from the interior bases of the moun- floor, rather widely separated and hitherto
tain border, the surface of Fracastorius gradually recorded. Between these and the crateriet s
rises so as to form a slightly convex floor, which a smaller one 1, also unrecorded. The appeara
culminates in what has hitherto been considered of Fracastorius on Rutherford's photogra
as a small central eminence or peak, but ascer- March 6, 1865, is extremely interesting.
tained by Mr. Ingall, on the morning before-men- dark tint of the Mare Nectaris has penetrata.
tioned, to consist of two craterlets, which, for the interior of the floor; indeed the mater
easy reference, may be designated a. These this portion seems to be of the same nat
craterlets are interesting, inasmuch as from them, that of the surface of the adjoining Man, :
in a S.W. direction, a line of very minute crater- tinuing its outline on the S., while the cot
lets (appearing in ordinary states of the atmo- of the two dark surfaces is interrupted by
sphere and in smaller instruments as a streak of N. border of Fracastorius, which is of the
light) extends to a craterlet b on the S.W. part of reflective power. A somewhat short re
the floor, which I observed with the Hartwell the S.W. border, given by Mr. Ingall, ene
Equatoreal on Sept. 13, 1862. From this latter this description of the floor of Fracaste
craterlet another chain of minute craterlets ex- very interesting lunar formation, which i
tends to a craterlet c, south of the pair a already to afford results bearing as much on impe
selenographical questions as those obtained
the study of Plato, if its craters' spots and
ings be observed with the same assiduity L
has characterized the observations of Plato,

It will therefore be seen that precisely the same mode of calculation may be traced through these eight cases, thus: For the plane surfaces named two dimensions are multiplied together-namely, length and breadth, and for the solids denoted these are further multiplied by the thickness. That for the circle and ellipsis the factor 7854 is used as a means of reduction from the rectangle corresponding; and for their solids, the sphere and spheroid, the factor 5236 as the measure of reduction from the cube and parallelopipedon. When once these reciprocal relations are mastered it is only necessary to burden the memory with the retention of the Two factors 7854 and 5236 to be completely master of the areas and solid contents respectively of EIGHT of the most important figures in practical geometry. To be thoroughly au fait at calculating these eight figures is thus a very simple acquirement, but not the less useful to the practical man; and yet what proportion of the total number possess this knowledge, ready at a moment without any book for jogging the memory? If called upon for an answer it must be confessed very few; in fact most look upon the ellipsis and spheroid as very recondite figures to deal with. The present little memoir has been written with the aim to show that it is not an abtruse question to deal with any of these figures. Beyond this its intention does not reach; it is in fact a purely simple and practical synopsis of the points touched upon, and if it should help any of the readers of the ENGLISH MECHANIC to a ready ease in dealing with the calculations treated of, its purpose will be fulfilled.

5

mentioned. This craterlet I observed on July 11,
1865. In addition to these objects Mr. Ingall
ascertained the existence of an-ther craterlet, d,
on the W. part of the floor, similarly connected
with the pair a by a chain of minute craterlets,
interrupted by a larger craterlet e, first seen by
Mr. Ingall on July 17, 1870. So far as I am
aware these minute orater chains have not hither-
to been detected. Clefts have been observed
within the interiors of lunar plains surrounded by
mountain borders, but these in Fracastorius are
so analogous to the well-known crater chains W.
of Copernicus, that further observation of them
is extremely desirable, especially with large in-
struments.

MOUNTING FOR THE MICROSCOPE.
BY "ACHROMATIC."

N laying before the readers of the ENGLIS MECHANIC Some articles upon mounting i the microscope I must beg to apologize to the other writers on the same subject for seemingly treading on their heels. In treating this subject I shall speak of the apparatus required in co junction with the method of mounting the object which may be under discussion, hoping by these means to avoid all ambiguity as to what instraments, &c., are required. And here I may mettion that most of the apparatus and a great many of the instruments can be very effectively mastÜ factured at home, as also can innumerable tile knick-knacks, the same designed by the ingenious microscopist, to suit occasions resulting frem his method of treatment, which as he gets more practised will be found, in all likelihood, to considerably differ from that of a brother in the art. In treating insects in my first chapter, the advanced state of the year must be my exense, and let me remind the beginner that he should lose no time in gathering specimens for future treatment.

There are two features of interest on the floor of Fracastorius-viz., a line of craterlets a little E. of the centre, and another a little E. of the W. border. These appear to be two nearly parallel lines of eruption, except at their S. ends, where they converge to a crater on the S. border of Fracastorius, given by Beer and Mädler, seen by me on July 11, 1865, and by Mr. Ingall on July 17, 1870. The first line of eruption consists of five craterlets, the southern one m seen by me Sept. 13, 1862, and by Mr. Ingall July 17, 1870. The next is the craterlet c, already mentioned, the third and fourth the pair a, and the fifth is a craterlet f, seen by me July 11, 1865, and by Mr. Ingall July 17, 1870. It is given by Beer and Madler. The direction of this line is nearly N. and S., and it terminates with a low mountain g, with at least three peaks, which I observed in 1862, 1863, and 1865, and Mr. Ingall in 1870. It would appear that between this mountain and the low hills forming the north border, indeed close upon them, is a somewhat shallow crater, seen by me on Sept. 22, 1868, and again on April 5, 1870. The second line of eruption consists of four craterlets and two spots of light n. The craterlets are b, d, and a pair of minute craterlets h. This line is terminated by two spots of light

CHAPTER I.

PREPARATION OF INSECTS.

Insects, like hares, have to be caught before they are " cooked," and this fact makes it im perative for the microscopist to make little excursions into the country (if he can), into a tom garden, or even into his cellar, and in fact anywhere where insects most congregate. And then the insect having been caught has to be killed, an for this nothing is more handy than a pocket death-bottle, made thus :

TO MAKE A DEATH-BOTTLE.-Having chosen a large mouth stoppered bottle of a size to sit. clean it well, then drop into it three or four good-sized lumps of potassic cyanide (half an ounce of this salt will be quite sufficient for a large bottle), cover completely with dry silver sand, and on the top pour a plaster made plaster of Paris mixed with about half its ball silver sand. Pour a thickness of this from h to three-quarters of an inch; when cover over the surface of the plaster with pa of loose blotting or filtering paper, cut @sh nearly fit the bottle. This is a perfect al bottle.

set" am

TELESCOPIC WORK FOR MOONLIGHT, as seen by Mr. Ingall, on July 17, 1870. These Besides this, I should recommend a sket

EVENINGS.

BY W. R. BIRT, F.R.A.S.

one to be made, small enough to be came about on the person at all times. This will b found extremely useful and convenient, for any day can be immediately consigned to oblivis without the least trouble; and in this way supply of insects will be found to be greath augmented.

spots I have usually seen, 1862, 1863, and 1865, as one, which is described in my earlier observations as "a round-topped table-land." On Sept. (V of Webb's index map) when the moon is appearance of a hill or table-land, no bright side, about five days old, will be found an object ap- no shadow. On the 22nd Sept., 1868, I recorded pearing immensely like a bay, indeed any one of "a round white spot is plain." July 1, 1865, Mr. the bays on our own sea coasts-Torbay, for ex- Grover described the object as "a crater." Mr. Inample-will furnish a fine terrestrial analogue.gall, July 17, 1870, speaks of it as a doubtful object, The name of this object, 372 of Webb, is Fracastorius. Surrounded on the W., S., and E. by a high mountainous border, the enclosed surface is separated from that of the Mare Nectaris by a range of very low hills, which appeared to Mr. Ingall (who observed them on the morning of July 17, 1870, with a dialyte of 5in. aperture, powers 196, 236, and 768) as if the soft mud (?) of the Mare Nectaris had flowed and almost covered some high mountains there, and had rounded off the asperities as if they had been washed with it. Mr. Ingall adds, this is somewhat romantic, but I express my ideas as they

O the southom border of the lure Nectaris 21, 1868, there was certainly not the slightest little insect that we to

which appeared as a double-light spot having no
shade. Between the mountain g and the spots n,
is, in Mr. Ingall's drawing, July 17, 1870, a hill
o answering to the "round-topped table-land"
mentioned above in appearance but not in posi-
tion. Mr. Ingall depicts three pairs of craterlets,
the pair a of medium size, the pair h very minute,

* Although Mr. Ingall's analogy of soft mud, &c., is not likely to be accepted by astronomers, nor is it put forth as supporting any theoretical view, it certainly expresses the idea of "invasion from the Maria," which is fully borne out by the appearances presented by all such for nations as Fracastorius.

The insect being now killed, should be passe on to the next stage-that of the potash-sapposing that it is to be mounted whole; if, however (as is more generally the case), it is to be dissected a proper book should be consulted, to ascertain what parts are the most desirable for preserva tion, and then the insect being dissected, ir accordance with this knowledge, these parts, a with the whole insect, are to be immersed in caustic potash.

But to dissect, certain instruments are required of these I think the scissors must be purchased. but small dissecting knives can be made by grinding sewing needles to an edge, and thea

mounting them in conveniently sized holders of out. In this, as in other things, the beginner
must remember that it is practice that makes
perfect.
(To be continued)

cedar or other wood. Of course these knives can be made of any size or shape to suit convenience.

In addition to the knives, plain mounted needles of various degrees of fineness, a few of them being bent (the bending should be done to suit circumstances), will be found extremely useful, and indeed necessary.

NEW SALT FOR INTENSE ELECTRIC
CURRENTS.

M.

necensed in this stage should be made DVD York Medical Journal, this platus solutions of nitric acid, in the following manner

in the following way :-
TO PREPARE POTASH FOR THE MICROSCOPE. To
the liquor potassae of the pharmacopeia add its
own bulk of water.

It will be found in practice convenient to have various bottles of potash of different strengths to suit the texture of the different subjects for preparation; generally three are sufficient.

The time that an object should be left in the caustic potash is a matter best determined by practice, but a little consideration will be found of great service, it being kept in mind that this alkali, while it dissolves flesh and fatty matter, leaves horny matter unacted upon.

The subject having been left in the potash for a time sufficient to extract all fat, &c., is immersed in as pure water as possible for four-andtwenty hours, the water being changed from two to four times during that period.

THE THEORY OF SUNSTROKE.
R. E. VAN DE WARKER, writing in the
the cause of sunstroke:-The integrity of the
cutaneous function is essential to the maintenance
of the equilibrium of the therinal condition of the
body. The perspiration is one of the principal
avenues of escape for the surplus heat generated
by the operations of organic life. While this is
true of the body when in a quiescent state, it be-
comes a cardinal truth when the body is in a state
of exertion and exposed to an elevated tempera-
ture. The healthy man, when exposed to these
conditions, at once perspires, and the temperature
of the system is preserved at a normal standard. If
this means of compensation between the systemic
heat and that of the surrounding air is impaired,
heat must accumulate in the system in reciprocal
proportion. To use a familiar illustration, the
evaporation of perspiration from the surface of
the body lowers its temperature in the same
mammer as the evaporation of water from the sur-
face of heated iron.

The object being taken out of the water should be well brushed with a copious supply of water. When the body is exposed to intense solar heat, The best brush for this purpose is a large the perspiration is the direct antagonist of the camel's-hair brush, costing one penny at any oil- sun's rays. When we reflect upon the amount of shop. With the brush the future object should heat necessary to evaporate one ounce of water, be arranged, according to taste, on a clean glass it is easy to see how the arrest of this function slide, and another clean slide being placed upon it, may lead to serious or fatal lesion of the vital the whole is placed in some convenient contri- fluids or nerve-centres. An ounce of water passvance for squeezing it firmly together. When dry, ing from the fluid to the vaporous state receives as the object is carefully removed from the slide and much heat as would raise its temperature to 990 immersed in good clear methylated spirit, where Fahr.; or, the quantity of heat required to conit is allowed to remain for three or four days to vert a quantity of water into vapour is five and a extract the last trace of moisture. The beginner half times as much as will raise it from the freezneed not be afraid of the spirit taking the forming to the boiling point. The evaporation from out of the object. From the spirit the object should go into methylated ether for two or three days, and if there be any bubbles of air in the object, it should be allowed to remain till they disappear. The object should next be soaked in the best refined turpentine for a couple of days; at the end of that time it may be considered fully prepared.

The object may now be mounted, and for this, of course, two glasses and a medium are required. As to glasses the thick slides had best be bought rady ent, the unground ones costing 4d., the round 8d. a dozen; but if preferred, the thin glass can be bought in sheets and cut at home, and, perhaps, with a small saving; but this saving is so small that it will hardly be found worth the risk of breakage, always incurred by an amateur. The medium for insects is generally Canada balsam, costing 6d. a bottle.

To mount the prepared object a clean slide should be placed on a piece of paper with its own centre marked thereon, and the object being taken from the turpentine, by means of the forceps, is laid over this centre, and all superfluous turpentine is wiped off with a dry camel'shair brush. A drop of balsam on a pointed glass rod is then let fall upon it, and a thin glass cover, nicely cleaned, is warmed, and being held by the forceps, is allowed to fall on the balsam, one side being more depressed than any of the others; the whole is then gently heated over a spirit-lamp, or a candle, when it will be found that the cover will fall down on the top of the object as the balsam softens by the heat. The cover should then be gently squeezed down with the top of the edle holder, and to keep the cover in its position till the balsam hardens a spring clip should be used. The superflous balsam should not be cleaned away in less than a month from the time of mounting, as it is apt to shrink and so admit air bubbles under the glass cover. This is our mounted object, and if care has been taken it ought to be good; no dirt, no bubbles, and no ilminess ought to be visible. As for its not being perfect, in the sense of complete, that is owing to bad manipulation, and is not a fault of the method of preparation.

the surface of the body of one ounce of perspira-
tion would transmit from the system to the sur-
rounding air all the heat required to accomplish
its evaporation. On the contrary, the arrest of
this secretion would lead to the retention in the
system of the heat otherwise expended in the con-
version of it from the fluid to the vaporous state.
The other excretory functions being impaired, it
would obviously require but a short exposure to
an elevated temperature to lead to an ac-
cumulation of a morbid degree of heat.
This is not an immediate effect; it is pro-
gressive. The impairment of function goes on
with the impairment of strength. The exhausting
march, or the stoking at the furnace, or labouring
in the field, is still continued, and, before the
victim is aware of it, possibly, the skin has ceased
entirely to act. There are now but few avenues
of escape for the systemic heat resulting from
muscular action, from the oxidation of tissue, or
from the hæmal oxidation of normal alcohol present
in the lungs, and still less escape from the alcohol
the man too often takes to relieve the exhaustion
from which he is suffering. In addition to this,
from the sun's rays the body is continually absorb-
ing heat, until such a degree of heat is present in
the system, that disorganization of the blood re-
sults, or the nerve-centres are so oppressed by its
presence that insolation (sunstroke) results. I
therefore conclude that insolation is the ex-
pression of the presence of a morbid degree of
heat in the organism dependent mainly on the
arrest of the cutaneous function.

ETEVE, of Paris, has taken a patent for the composition of a salt for the production of very intense currents of electricity, which he calls double acetate of iron and potash. The inventor claims to remedy the inconvenience arising from nitrous exhalations disengaged from The nitric acid is replaced by a salt composed of one part of sulphate of protoxide of iron and one part of nitrate of potash, dissolved in a sufficient quantity of the ordinary acetate of commerce, the solution being aided by a slight heat; the whole is then left to cool and crystallize, and the crystals after being drained, are stove-dried. When the salt is thus prepared, the pile is mounted in the following manner:-In the 'non-porous vessel is placed a saturated solution of common salt, and a zinc cylinder is introduced, within which is placed the porous vessel containing the charcoal, upon which is poured water containing 30 per cent. of sulphuric acid. In this state the pile will not act, or in an almost insensible manner; but, in order to develop the current, it is only necessary to introduce a few crystals of the above-named double salt, when the current becomes remarkably intense, if not superior to that of the common pile; the current may be easily maintained constantly and regularly by merely adding a few crystals from time to time, and without any nitrous vapours being disengaged. M. Etève believes that his salt is a double acetate of iron and potash, but a writer in the Moniteur Scientifique objects to this, and says that if small quantities of this salt are formed, as is probable, with the aid of the acetic acid, the greater part consists of two sulphates and two nitrates of potash and iron. He believes that the activity of the salt in question arises from the fact that the small quantity of the acetate of protoxide of iron, finding itself in the presence of a nitrate of the same metal, becomes peroxidized; heat as well as electricity will bring this about. This is the salt that has proved of so much value in the dyeing of black silk, and which is improperly called nitro-acetate of iron. All who have attempted to reduce nitro-benzine by ferrous acetate know how rapidly this converts nitric acid into ammonia. Gun-cotton may also by it be brought back into the natural state of cotton. It is, therefore, quite natural that no nitrous vapours should be evolved from a pile fed by such salt. Perhaps nitrate of soda might be substituted for nitrate of potash with economy.

THE FLUTE AND ITS VICISSITUDES.
BY SABLE.

THE

(Concluded from page 558.) HE alleged improvements of the Böhm flute awakened great expectations" in the minds of flute-players generally; but all pleasant anticipations were at once dispelled by the appearance of the instrument itself, and with few exceptions its introduction was strongly opposed: it was accompanied, too, by a number of new students having little or nothing in common with the staid Nicholsonians, who treated the old flute with contempt, voted it "obsolescent," and answered all opponents with the full, firm tones

of the Böhm. This was rather too much for the oid flautists, some change and remodelling they had expected, some fresh difficulties they were prepared to encounter; but here was a metamorphosis in which they could recognize nothing of their old acquaintance save its head, and even the fashion of that had been altered: here was a flute to be studied afresh from its very gamut; something to be acquired and something to be forgotten simultaneously; moreover, it was pertinently objected that what had already been so changed and complicated would in all probability undergo further mutation at no distant period. Meanwhile, the new instrumentalists gained ground, and the old stagers, who would not go to school over again, either eschewed the flute altogether or retired disspiritedly from the contest; hence all not personally interested in the matter ceased to study the flute, and the popularity of the old favourite at once declined.

The preventives recommended by Dr. Van de Warker, are the wearing of a white shirt over the flannel, if that is dark coloured, covering the neck and chest, and wearing a light straw or palmleaf hat, with fresh leaves or a wet handkerchief in the crown. The working man should always attend carefully to his diet, and never work exposed to a high temperature while suffering from the calls of hunger. Ardent spirits should be avoided. The violent reaction following over-stimulation is attended with most serious effects when the subject is exposed to a high temperature. When men experience a sense of fulness in the head and of tightness across the chest, The above process may, perhaps, be considered with a total or partial suppression of the perong and tedious, but it is really not so; that spiration, they ought immediately to stop work you have to wait a long time for the completion and protect themselves from the sun's rays until of the preparation I admit, but then it does away the functions of the body are restored. Persons with all necessity for an air-pump for extracting in infirm health or convalescent ought to take i-bubbles, &c., for with a little care air does not extra precautions when exposed to severe heat. and cannot (by reason of the object, up to the trying process, being filled with some liquid or ther) get in. If, however, it does get in a few lays extra in the ether will generally drive it! are wanted for 500 grammes of saffron. Sixty-nine thousand one hundred and twenty flowers next claims attention, and the open B flat key

The reader is referred to Fig. 1, the Böhm flute, the drawing of which shows the open C natural, or thumb key e; the open G sharp key

b, acted upon by the lever of the ring a, second

FOOT

FIG 3

FIG 9

finger of left hand, also by rod of the ring c. first finger of right hand; thus to produce B flat the first fingers of each hand are pressed down; the ring c also closes f, the open F sharp key, in fingering F natural; and the ring d, third finger of right hand, shuts f by the aid of the lever in producing F sharp. The awkwardness of these B flat and F sharp fingerings to a flautist of the Nicholson school can only be duly estimated in their acquirement. It is scarcely necessary to apologize for the open-keyed system; every fluteplayer is aware that the tone of the instrument is much improved by keeping the D sharp key open when it can be done (in rapid arpeggios in the chord of F natural, when the F natural key can were insufficient to displace the Böhm, the Dorus upon the weak fingers. The cylindrical bore was be "secured "-e.g,, as when E and C do not modification of which still held its own both in brought forward as a new thing; it was not so: occur in the passage, the increased fulness and England and on the Continent. Fig. 2 is an ac-fifes and the old flute a bec (p. 411, had been con freedom with which the flute speaks is very curate representation of the Diatonic or Sic-structed so long before; the conical head joint evident, especially in the fundamental octave). cama" flute; there are two finger rings at d was no novelty, the clarionet and organ pupes Such was the Bohm, or first open-keyed flute, which command the open key between them, by were old examples of crocs in the heads of musi practically useless to those who would or could which arrangement the C sharp is much improved cal tubes. Under these circamstances, Mr. not begin as upon a new instrument. A carefully in tune and firmness; there is a finger plate at a Clinton himself commenced a series of experi made drawing is given, it having played so in- which closes the open key covering the G hole, ments, the result of which was a cylinder dute portant a part in the flute's history, and it is the and at b is a similar contrivance for "stopping with the simple and natural expedient of regularly foundation of that system which has been applied the E hole (as both these openings are placed graduating the holes. Fig. 3 shows the old cyander not only to all modern flutes, but to all instru- beyond the reach of the finger), which decidedly with its equal-sized holes; Fig. 4, the new o ments of its genus. That distinguished professor, improves the respective notes. The F natural with regular gradations. It is true others have the late Mr. Clinton, was one of its earliest and key is also situated lower in the body of the flute. declared that cylinder flutes with graduated warmest advocates. After comparing its system In this instrument the same theory of equal-sized were made by them prior to the appearance of carefully with that of the old flute, he was holes is strenuously maintained, although it is the "Clinton cylinder," and that the said he so convinced of its superiority that he adopted tuned "on strictly acoustical principles." "The decreased regularly always one quarter of it himself and recommended it to his pupils; weak and ineffective quality of several intervals a millimetre " (about 1-105in.) "in diameter. but in doing this he encountered a storm of on the old flute, occasioned by the disproportionate Be this as it may, such a gradation would have opposition. However," he writes, "those who size of the holes, and the inequality of their re- no practical influence on tone or tune, even if were my most vigorous opponents, after spective distances, is entirely remedied on this could be accurately marked on the flute's rou a while became my warmest supporters; flute, where they are of an equal character surface. It would be beside the purpose and I was confident that the decided supe- throughout and partake of the same firmness and commend any particular flute, but if we an riority of this flute would eventually over-power." "For A an aperture equal in size to to have what has been so patiently and come the prejudice with which it was at first rethe preceding ones,-thus a clear and brilliant triously sought, I think we have got it garded." The open G sharp key, nevertheless, A is obtained," &c., &c. Now if all these Clinton Cylinder; nor are spectacles needed to s was found to be so troublesome that M. Dorus, of fine theories be right, dame Nature must us that the natural laws of sound have not be Paris, changed it into a shut one, adding a ring have made a rare hash of her acoustics! but violated; the old system of fingering is reta for the left hand third finger. This change was seriously; it proves what a fascination equal- and the long cramp F natural key disca adopted by Mr. Clinton, in 1842, and slight as it sized holes have had for flute manufacturers. there is also a means of taking this note wi was it gave rise to more dissatisfaction and susIn the interim, pockets were lightened, and first finger of the right hand, as on the F picion. Herr Böhm had astonished the natives" the purse of the exchequer made heavier by the but this involves no alteration in the finger with his invention, a Mr. Cornelius Ward, how- patents granted for all these contrivances; flute the F sharp, or the old fingering of the fort ever, surprised both natives and foreigners with players were dissatisfied and undecided, and a very singular species of flute, and he increased inakers worked up to a great pitch of competition their surprise by assuring them in a pamphlet and contention, each one earnestly affirming that on his system facilities were offered by that his instrument was the " werry identical sundry cross and back fingerings: it is true that flnte," and all others were "abortions." M. this flute was professedly free from such abomina- Tulou, of Paris, added another faggot to the fire tions, but be it ever remembered, that all depar- by substituting two thumb keys, one for C natural, tures from the old mode of fingering (which is and the other for B flat. And now the talented decidedly the best because based upon simple and Mr. Carte, in conjunction with Messrs. Rudall & natural laws) is practically a back or cross finger- Rose, brought out two new flutes, and in a thought ing. Mr. Ward's contrivance had five keys for ful treatise, lucidly stated the fact that the flute's the work of the left hand thumb, three of which condition was as yet highly unsatisfactory. Mr. acted on the foot keys; they were in reality Clinton appears to have applied to the patentees apologies for "duplicates," to obtain slurs, &c., of the Böhm flute on the subject without avail; not available before, and the result was that however, he went to Munich to consult with Herr neither the old or new were accomplished well; Böhm, who, some little time after, brought over this flute was to dazzle all the orchestras in his metal flute with parabola head (like the Europe, but its fame was circumscribed, its exist- clarionet) but it did not meet the difficulties in ence brief, and it is scarcely remembered. A the estimation of the former gentleman. One drawing of this musical curiosity would have been would have imagined that the Böhm flute, in the presented, but that it served no useful purpose in hands of a proficient, was all that could be flute regeneration. A Mr. Card next presented desired, but it was not so; players of moderate himself with a flute that was to "make these capacity, it is true, found a certain ease in getting odds all even,"-it was neither more nor less than out the lower notes, but the intelligent student "Böhm" in which the right hand part was soon discovered the host of evils with which he altered, while the left remained as before; this had to contend; the notes of the third octave died almost in its birth and was soon thrown were painfully sharp and thin in quality, owing to aside. The next claimant for favour was the the largeness of those apertures serving for the flute of Mr. Siccama, B.A., formerly known as time as holes; the lowest note (C the "Diatonic," and it did good service to the natural) was a very fine one, the D, iramediately cause inasmuch as it reverted boldly and steadily above it, weak; the whole temperament of the to the old system of fingering; it possessed many cylinder very unequal; there were several very advantages over the Nicholson flute, but they awkward fingerings, and a deal of work imposed

a

vent

My task is done, and I have to acknowledge care and accuracy with which my drawings a been reproduced; and I must, en passant, esp my admiration of the beautiful engraving machinery, which are constantly given s periodical. And now I bid adieu to the fa of the ENGLISH MECHANIC with hearts wishes both for themselves and our Although no longer able to use or enjoy ite the satisfaction of knowing they Finally, I entreat all to believe that I kept steadily in mind the motto which had these papers

Nothing extenuate,

do both.

Nor aught set down in mahce. ERRATA.-P. 459, 26th line from bottom-lor ** read "his." P. 558, 39th line from top-for "172"*. 1828." THE END.

COFFEY'S APPARATUS FOR DISTILL
TION.

S several correspondents have asked for formation concerning Mr. Coffey's re inventions of apparatus for distillation, evap tion, &c., we give an illustration of a portic that in use by Messrs. Doulton & Watts Lambeth. The invention of Mr. Coffey cons in the application of the discovery that a so paraffine oil may be continuously heated in ci tubes to a temperature of 1100 Falir.-in o words, to a temperature at which iron exhib