ENGLISH MECHANIC AND WORLD OF SCIENCE: No 1,008. bourhood. Between Wollaston and Delisle a, the JULY 18, 1884. STELLAR CHROMATICS. sonnel de M. Rabache prophète de M. Béron, et 1866, and the extraordinarily sudden appearance of [23002.]-J'AI gardé le meilleur souvenir perl'un, ni l'autre. Mais je serais fort embarrassé Schmidt in 1876, and then who will say that even a readers of this paper; but let them bear in mind the sudden increase in the lustre of T Corona in de répondre en détail aux nombreuses et complexes sudden change of colour in a star is impossible? Is depuis bientôt vingt ans, je ne les ai oublies, nia new star in Cygnus, discovered by the late Prof. questions de la lettre 22952, et je ne puis que renvoyer votre savant correspondant à mes derniers to enable us to say it is not within the range of our knowledge of the sidereal universe so perfect as Mr. Neison quotes Mädler as saying that étudiées, et où il pourra reconnaître que je suis fort one has been known to occur and the other has ouvrages, où elles sont à peu près toutes, je ne possibility? Why should one be more extraordin Argelander dis only seven days free from shadows. loin de ne pas rendre publiques les choses que nous not, and therefore one appears more probable than dirai pas résolves, assurément, mais examinées et ary than the other? The only difference is that It appeared to me, when observing it, that it was free from shadows for a longer period. I have pouvons savoir. therefore watched it for some months, with the que, si je ne professe pas une admiration servile result that it seems to be at least nine days free, pour "la Science Officielle," à laquelle, je ne crois tion des étoiles colorés est à la fois des plus intéresand I believe the time is longer. A curious fact is guère, ce n'est pas une raison non plus pour que should think might be taken up with advantage by Qu'il me permette d'ajouter that the floor is sometimes a light grey, and some-Je doive me faire l'écho de théories de certains such a working body as the Liverpool Astronomical As M. Rabache (22952, p. 393) says, On August 22, 1883, I was observing the plain E. pas officiels. Tel est le cas de M. Béron, dont les tions are to be made, the observations of various santes et des plus graves," and is a subject that I savants independants par ce seul fait qu'ils ne sont Society, it being a subject in which, if eye estima times a very much darker shade. of Burg with a 4in. telescope, and power 168, and saw the cleft very plainly, which confirms Mr. Elger's remark in this month's "Astro. Register, that all the clefts in this plain are not so difficult as Mr. Neison supposes. It crossed one ridge on wall of Burg. From the S.W. corner of the plain the floor, but not another which springs from the starts a peculiar, very straight and brilliant, narrow short ridge. At 14h. 20m. I thought I could make out part of the cleft at the foot of this ridge. On Feb. 2 the cleft was again plainly visible. There is a small, but very conspicuous, crater on the Mare Imbrium, a short distance north of Eratosthenes, which is not shown by Mr. Neison. It is the size of the largest of those between Eratosthenes and Copernicus, and when I saw it in 1882 it was partly filled with deep shadow. M. A. SELENOGRAPHICAL-MARE CRISIUM [23000.]-IN reply to Mr. S. Maitland Baird I have Will Mr. Elger say if, when he observed his two clefts N. of Reinhold (letter 22723), he noticed any ridges running along them? On July 2, 1884, through very bad air, I saw at the place occupied by his clefts a formation having the shape of a Greek y, evidently formed by ridges, and given as a succession of craterlets by Schmidt. The power I used was too low to show delicate clefts," which must run at the foot of those ridges. Just N. of the above object there is another formation having nearly the same shape, with a craterlet between their tails. I have observed three white streaks crossing the floor of Albategnius, and I have some reasons to believe they are very fine crater rills. Two larger craterlets are on two of them, and I have seen a few other objects on this floor besides the central mountain. Has any selenographer anything to say about this floor? ERRATUM.-Letter 22953, line 16 from end, after add "Boötis." C. M. Gaudibert. POLARIS [23001.]-THE Rev. Mr. Webb, p. 411 of "Celestial Objects,,' says that two nearer companions seen by de Boe, 1869, and confirmed by others, were denied by Burnham at Chicago. Although I have frequently examined this object, it has never been my good fortune to see more than the well-known companion; but on Sunday night, the 6th inst., 10 p.m., I and two friends distinctly and steadily observed a second companion S. of Polaris, and one of the party with remarkably keen sight declared she saw a third very close to the principal and n. f. The upper one which my friends described as forming the letter L reversed, we observed for one hour as a 10m. star, being somewhat less bright than the companion. 7th July, 10 p.m. Had I been alone last night, I should now doubt my senses. The stranger is no longer to be seen, although the blue (?) companion to Polaris is bright and clear; but my lady friend still persists in seeing the close companion n. f. The optical means employed were a 5in. Cooke, with powers of 60, 120. Should like to know whether any other observer with adequate means saw this remarkable object on the 6th inst. Lake, I. of W., 8th July. Wm. Bians. ouvrages quelque laborieux qu'ils soient, ne me Rabache leur attribue. logue d'Etoiles doubles." Si M. Rabache l'avait the other. of " ours 99 work? "La ques observers, with all descriptions of telescopes, and in as M. Montigny's apparatus, described in a number is, however, desirable that some such instruments every condition of the atmosphere, are required. It scope, described by me in Vol. XXXIV. of this by "F.R.A.S.," or the Astro-chromoveut bien la regarder plusieurs soirs de suite, il instruments constructed, and add the instrumental rouge, quoique cela paraisse lui faire de la peine. Quant à l'étoile a de l'Hydre, si M. Rabache no observatory that can afford to have one of these journal, should be more generally used. Is there verra qu'elle est parfois jaune et parfois jaune-determination of star colours to its other routine Pourquoi ai-je écrit que les étoiles rouges parais- competent observers, such as Mr. Espin and mill's letter, respecting the extent to which the sent être les plus agés ? I should much like to have the opinion of some duplicity of stars influence their colour." I should expect with Mr. Gemmill that, in those cases in "F.R.A.S.," upon the point raised in Mr. Gemwhich the stars were comparable in magnitude, and the colours not complementary, that when they were viewed with a power too low to divide them, the apparent colour would be the resultant of their combination. B. J. Hopkins. brillant qu'un seul d'entre eux est visible à l'oeil mill's query (22922, p. 365) respecting the achro- Dalston, E., July 7. the apparent colour of a star is evident from the VAGARIES OF LIGHTNING all the scientific treatises which have appeared on server. This suggested sudden and brief change of colour will, no doubt, appear absurd to some of the on. A very vivid flash of lightning, attracted by A fortnight ago a lady of my acquaintance was the metal, actually singed off part of her eyebrows out of doors with a pair of steel-rimmed spectacles [2 3006.]-I AM not sorry that the short dialogue which appeared in your columns a fortnight ago has evoked so many letters on a most instructive subject, because my intention was not to propound thecries, or to set up as an expert in a science with which so many others may be more familiar than myself, but simply to express in words what is, at all events, considered a popular explanation, and thus to advance the progress of knowledge. The object I have now before me is to substantiate on authority the statements contained in my communication, which, rightly or wrongly, are called in question. Calculation. Observation. ft. in. Error. +1 ft. in. 16.. 23 17.. 7 22 10 21 7 18.. 8 22 10 11 19.. 23 22 11 20.. 3 1 James Pearson, M.A., F.R.A.S. THE OTTO BICYCLE. The answer to my first interrogatory states that "a thunderstorm is an atmospheric disturbance caused by the sudden transfer of a large quantity of accumulated electricity between the clouds and the earth." Referring to Silvanus P. Thompson's "Elementary Lessons in Electricity," page 255, we have the following remarks on the theory of thunderstorms:-"The clouds are usually charged, more or less, with electricity, derived probably from evaporation going on at the earth's surface. The minute particles of water floating in the air, being better conductors of electricity than the air itself, become more highly charged.' And, again, "by the coalescence of the drops and the electrification at the lower surface of the cloud the potential will become greater and greater, the surface of the earth beneath acting as a condensing plate, and becoming inductively charged with the opposite kind of electrification. Presently the difference of potential becomes so great that the intervening strata of air give way under the strain, and a dis- It is not necessary for me to answer in detail the ruptive discharge takes place at the point where the several paragraphs in the letter of "Antares." The air offers least resistance." I think this quotation theory and practice of the machine were thoroughly is in perfect harmony with what is stated in the re-explained in a series of letters in the "E. M." which plies to the second and third answers to the queries appeared last year. I may, however, remark that in my dialogue; at all events I intend it should be the perfect and unconscious management of the so. Again, on consulting Ganot's "Physics," page Otto depends upon the development of a muscular 946, it is said, "Volta first showed that the evapo- sense, which is very rapid with young people, but ration of water produced electricity;" and he adds which must be slower with grandfathers. lower down, Reasoning from experiments, "Antares" must, therefore, practise on gradually Pouillet ascribed the development of electricity by increasing slopes until he finds it a pleasure running evaporation to the separation of particles of water down steep places. He should, if possible, go out from the substances dissolved; but Reich and Riess with some experienced rider, for I have found, and showed that the electricity disengaged during eva- many other members of the Otto Club will bear me poration could be attributed to the friction which out, that one run with a few good riders does more the particles of water carried away in the current to make a beginner proficient than weeks by himself. of vapour exercise against the sides of the vessel, The remark that the Otto is suitable for good and just as in Armstrong's electrical machine." level roads only does not tally with the experience of riders; the worse the conditions the more does the Otto shine by comparison with other machines. I should add that my remarks apply only to the modern Otto with the rubber-lined bands and the band brakes. He further states, "The formation of positive clouds is ascribed to the vapour disengaged from the ground and condensed in the higher regions. Negative clouds are supposed to result from fogs, which, by their contact with the ground, become charged with negative electricity, which they retain on rising into the atmosphere; or that, separated from the ground by layers of moist air, they have been negatively electrified by induction from the positive clouds which have repelled into the ground positive electricity. Whatever be the origin of atmospheric electricity, there can be no doubt that the invisible aqueous vapour is the carrier of it." Hence, I think it is hardly true to say, as "Rho" does, "that the friction theory will not hold." And I also am puzzled to find how "Sigma" bas discovered that my description is "based on the theory that electricity is a fluid or fluids." But I am willing to admit that the explanation of the deluges of rain which accompany thunderstorms is vague and indefinite. The quotation from Herschel's "Meteorology" seems most appropriate on this point, as cited by "X. N. X." I do not intend to enter further into the subject, being satisfied on having attained my object, and Perhaps those who remember the results of my ball weighing experiments will be surprised to hear that they point to one conclusion of practical importance. Up till March I removed one set belonging to the right wheel every 200 miles, washed them in benzol, and weighed each very accurately. The average loss per 1000 miles on the set was found to be 0.00308grm. After that I ran 2,160 miles without touching them. The loss after this showed an average wear of 0.0006grm. per 1,000 miles-just onefifth of that obtained before. The probable reason is that the wear occurs in the first two or three miles while the few grains of grit, which it is impossible to clean out of the screw, but which get dislodged in the screwing up, are being ground up, and then the wear is inappreciable even to the refined sense of the most delicate instrument. The conclusion at which I arrive, therefore, is that as long as the bearing is working properly, which may be known by the oil escaping clear (I found the oil on the balls perfectly clear), the bearing should not be opened. That everlasting desire to clean the bearings has the same result as the corre sponding desire to be always cleaning water cisterns. In the one case particles of grit lodged in any crevice get displaced, in the other, all the beasts and vegetables which were sleeping harmlessly at the bottom are stirred by a besum and set swimming around in a renewed state of activity. Bearings, when new, and after a few hundred miles use, should be cleaned; after that they should be let alone until the escaping oil shows that they require C. V. Boys. attention. [23009.]-I HAVE been riding this machine three seasons, and now find no difficulty in des ending steep hills. The steering down inclines is certainly difficult at first, and it took me quite a year to thoroughly master it, but now all difficulties in this respect have vanished. The same remark applies to uneven roads, when, as "Antares" says, the usual rules for steering are converted into exceptions. The Otto is not constructed for a hill climber, but I consider it better for hilly districts than most tricycles which are not geared down. It has the disadvantage that the feet must always be kept on the pedals, even when gravity is taking the machine along, but the delightful motion, so free from jolting, makes up for this. I consider the Otto is sadly in need of improvement in the driving arrangements; at present a half inch steel ribbon drives on a pulley lined with rubber, the rubber wears out quickly and unevenly, and the bands are apt to slip a little with rain; to remedy this last defect the company have lately used driving bands lined with rubber; these certainly "bite" well, but are not to be relied upon for wear -mine stripped right off after a shower of rain. Rubber has always been found bad wear for friction driving, and the sooner the Otto makers give it up the better. Why should they not use a triangular band of leather running in grooves, or, better still, adopt the centre chain driving of the Humber tricycle, the main axle to be driven by this, and the wheels to be attached to it by cone friction clutches, to be loosened for steering by handles as at present. Buzz. THE PANTANEMONE OR UNIVERSAL WINDMILL. [23010.]-I WAS SO much interested in the account of this machine, that I set to work and made a model of it. The discs are 8in. in diameter, fixed on a tin. square spindle of wood with brass pins in the ends, supported by two uprights from a plain board. It certainly seems to bear out all that is said of it, as it ran very fast even while laid on the ground. be I was in hopes some observations would have been made upon it by some of our readers in last week's paper, but none having appeared I take the liberty of ventilating it. In past volumes there have been a number of plans of windmills, but none of them seemed in any way superior to the oldfashioned four-armed mill. Now that power is wanted for electric lighting, driving lathes, pumping water, &c., I think this mill would be a great help for these purposes. In order to enabled to construct a mill on the large scale, I should like to be informed how the sails or vanes are constructed as regards framing, and whether covered with canvas or metal? Also what would be the size required to develop, say, 1-horse power in a moderate wind? I have an idea that the semicircular form is not the best for developing the whole of the power to be got from this mill, and intend to make another model with the vanes shaped according to my ideas. I also think the principle could be used for ventilating or exhausting purposes, as I found it gave a current of air strong enough to blow out a benzoline lamp, by merely being twirled round with the thumb and finger. H. C. B. THE HEALTH EXHIBITION. [23011.]-THE following question must arise in the mind of any intelligent visitor to the Health Exhibition-Have the luxurious and expensive furniture and art decorations of which threefourths of the Exhibition consists anything to do with health? If this question is answered in the negative, nothing further need be said on the subject; but if in the affirmative, this corollary follows-viz., that only the wealthy can enjoy health. The absurdity of this is obvious, so we must seek elsewhere for the "health" part of the Exhibition. If we go to that unfrequented and elevated room, No. 15, at the top of the City and Guilds Central Institute of Technical Education, we shall find in the Biological Laboratory, under the care of Mr. Watson Cheyne, M.B., F.R.C.S., and his assistants, the germ of the whole Exhibition. Here will be found one of the most interesting and important exhibitions that has ever been shown to the public in this or any other country. Not having seen any account of it, I take it as my duty ENGLISH MECHANIC AND WORLD OF SCIENCE: No. 1,008. JULY 18. 1884 received the stereotyped reply that the sliding tube and concave mirror were good enough for histofind that Messrs. R. and J. Beck are not going be guided by an old-worn phrase (however eminent logical purposes." I am, therefore, very glad to to keep the student's microscope up to date. It behoves us all to remember that Nature's histological secrets lie a good deal beyond the reach of our most powerful microscopes, and that if we are may be the person who originated it), but intend to make any headway in their discovery we must not put obstacles in the path of instrumental improvement. exhibition of apparatus, well worthy of the high reputation of that firm. It contains a No. 1 stand, a full-sized binocular on simple tripod, bar movement to body, rack and pinion, coarse adjustment, Messrs. Powell and Lealand have a beautiful fine adjustment, 50 thread screw geared down by 2:1 lever. lin. of rectangular mechanical motion, and complete rotation of stage by wheel and pinion. Stage plates graduated to Olin. for finders, Substage has mechanical rectangular and rotary motion, and mechanical coarse and fine focussing adjustments. Plane and concave mirror, on double jointed arm. This instrument has also a separate monocular body. 10in. bodies, bar movement, coarse and fine adjustment as in No. 1, mechanical rectangular stage. Substage with achromatic condenser, with mechani cal centring and coarse adjustment movement. A portable binocular microscope on tripod stand, Plane and concave mirror, on double jointed arm. It has a separate monocular body, and packs in a small case with the usual apparatus. and privilege to set before my brother readers of micrographic apparatus and heliostat, 12 beautithe ENGLISH MECHANIC a short epitome of the work ful diagrams, illustrating fungoid diseases in done there. I wish the task had fallen into abler plants, by Worthington G. Smith; hauds than mine, for, the subject being a medical plant, which was last year healthy, and on May one, any account given by one not a member of 22nd was inoculated with germinating spores of the profession must necessarily be imperfect: but Puccinia graminis from wheat straw. a barberry as the subject is also intimately connected with the 30th, spermagonia first grew, causing yellow spots microscope, it is chiefly in its microscopical aspect on the leaves. At the present time, there is a good that I intend to treat of it. To begin with, this development of oecidium berberidis. On the walls biological laboratory is a place where micro- there are some very interesting tables, showing, On May organisms (known as microbes on the Continent) diagrammatically, the death-rate from small-pox in are isolated and grown, the whole process practi- various countries; and I would earnestly entreat cally illustrated, and the various apparatus and all those who are opposed to the vaccination laws appliances connected with the subject exhibited. to carefully study the death-rate from small-pox As scientific research into the life-history of micro- in those countries where re-vaccination is comorganisms is of comparatively recent date, and as pulsory. There is a very ingenious aspirometer for some of your readers may possibly not have followed determining the number of germs in a given the investigations of Lister and Tyndall in this quantity of air. It consists of a glass tube about country, Pasteur in France, and Koch in Germany, it 2ft. 6in. long, and 1țin. in bore, on a tripod stand. will be as well to recapitulate the results of some of One end of this pipe is covered with a diaphragm their observations, so that we may intelligently of indiarubber, with a circular hole about tin. in grasp the subject before us. In the first instance, diameter in the centre of it. This is again covered it was found that the phenomena of fermentation by another indiarubber cap. The other end has an and putrefaction were due to the growth of micro-indiarubber plug, with a small glass tube through organisms, and that these micro-organisms were it. This pipe is connected with a bottle of known not spontaneously produced, but dropped into the capacity, filled with water, which is similarly substances from the air. It was found that at connected with another bottle. certain high temperatures these micro-organisms of using this is were killed; that if certain substances ordinarily tube having been coated on the inside with susceptible to fermentation or putrefaction were sterilised gelatino-meat infusion, the outer indiaThe method placed in sterilised flasks, having their orifices rubber cap is removed, allowing free passage to the very simple. The large closed by a plug of cotton-wool, no fermentation or air through the diaphragm in the second cap. A putrefaction would take place. It will be noticed known quantity of water is siphoned out of the that the substances were allowed contact with the first bottle by means of the second bottle; consegases in the air through the cotton-wool, the cotton- quently a known quantity of air is drawn along the wool merely filtering the air, and thus freeing it large glass tube through diaphragm at the other from the germs it contained. So much for micro- end, the germs being deposited on the gelatino-in power from a 4in. to ath. Of these the followorganisms in general. Now we come to the great meat infusion. discovery of Dr. Koch, which is of such funda- germs allowed to grow, when they may be counted, commonly to be met with: a rd39 N.A.; 3rd -76 mental importance that it may be called the basis cultivated, and examined. By means of this gelatino- N.A.; water immersion, 1-17 N.A.;th homogeneA set of 24 object glasses, not in boxes, ranging and starting-point of this new branch of science. meat infusion the veritable dangerous organisms ous immersion, 1.47 N.A.;th dry (date 1857) triple The tube is sealed up and the ing glasses may be especially mentioned as not It is a method whereby these excessively minute in "the water we drink" may be isolated and ex- front, 94 N.A.;th water immersion, 12 N.A.; micro-organisms may be isolated, and so a pure amined. They will be found to be very different cultivation of them be obtained. The secret of from those well-known forms of Dytiscus marthe system lies in using a gelatinised meat infusion ginalis, Daphnia Pulex, &c., thrown on the screen as a cultivating medium. I will endeavour to make in the large theatre of the Polytechnic, and often this clear by means of an example. On the table seen in the puffs of the vendors of filters-a bucket was a glass dish, in which was a shallow layer of of which, while being very disagreeable, would gelatino-meat infusion, which had been sterilised nevertheless be as harmless as shrimps. It is only and then exposed to the air of the room for five necessary to mix a small quantity of the water minutes, a few days previous to my visit. It was placed in an inclosing glass vessel, whose orifice meat infusion, then spread it over a flat, sterilised was plugged with cotton-wool. On examining the plate of glass, and keep it from further inoculation to be tested with some of the sterilised gelatinosurface of the gelatino-meat infusion a number by the air while the germs are growing. In this of spots were seen, red, white, black, brown, connection it would be as well to mention that so yellow, and blue in colour. These spots are caused exceedingly minute are these germs that there is by the growth of the various organisms which fell probably no filter at present constructed which is on the gelatino-meat infusion during its five capable of freeing water from them. minutes' exposure to the unfiltered air of the room. safeguard with suspected water is to boil it. The Now, if a pure cultivation of the organism that stains used in this laboratory are prepared by Dr. produces, say, the red spot be required, it is only Georg Grübler, and may be obtained from C. necessary to inoculate some sterilised gelatino- Baker, 244, High Holborn. The sterilisers and inThe only meat infusion from the red spot by pricking its cubators are by Dr. Hermann Rohrbeck. Leaving surface with a needle which has touched the red this important part of our subject, I must pass on spot. This is done in such a manner as to insure to the microscopes. no contamination with other germs, and then the vessel containing this inoculated gelatino-meat infusion is closed with cotton-wool. Some of these germs will only grow in certain temperatures. In these instances the inoculated tube is placed in an incubator. Several kinds of these incubators are exhibited. The main feature in all is a metal box with a double casing; water is placed in the double casing, which is heated by a gas-flame; an equable temperature is maintained by an automatic valve, which, by the expansion of mercury, regulates the supply of gas to the burner. There is a means of adjusting this valve so that any required temperature may be maintained. A number of test-tubes, about one fourth full of gelatino-meat infusion, containing pure cultivations of the following organisms, from Dr. Koch's laboratory in Berlin, are exhibited on the table. Bacillum: of rabbit septicemia, chicken cholera, znouse septicemia, authracis, of blue pus, green pus, causing fluorescence, causing violet colour, of enteric fever, of glanders, of tubercle, of blue milk, of lactic fermentation, of butyric fermentation. Micrococcus: tetragonus, of erysipelas, of pneumonia in man, of osteomyelitis, causing no change in milk; Sarcina; Mucor; Aspergillus niger, albus, flavescens, fumigatus; Oidium lactis. The next objects well worth careful study are 36 photo-micrographs by Dr. Koch, interesting not only on account of the subject of the photographs, but also because of the extreme difficulty there is in photographing such minute organisms at all. The subjects of the photographs are as follows:Septicemia in mice, splenic fever, pyæmia in rabbits, erysipelas in man, progressive necrosis of tissue in mice, recurrent fever in man and monkey, osteomyelitis, diphtheritic inflammation of bladder in man, progressive formation of abscess in rabbits, small-pox in man, pyelonephritis, ulcerative endocarditis. the EXHIBITION CASE BY MESSES. R. AND J. BECK. th homogeneous immersion, 143 N.A.; th Pleurosigma formosum, x 3,000 diameters; Navi- 9 microscopes :- 1. Student's microscope, non-inclining, direct 2. The same, only inclining, glass stage, plane and concave mirror. called a pathological stand. It consists of a body fixed by a compass joint to a single pillar on a flat Ten Microscopes.-The prevailing pattern is that tripod base. They all have substages with centring gear and coarse adjustments. The body adjust-justment, mirror in single joint. ments are rack and pinion coarse, and for the most part direct-acting screw fine. lever of the second order is interposed between the adjustment, direct screw fine, graduated rotating 3. The same, with rack and pinion coarse adwork and the screw. 4. A Wale's microscope, swinging mirror, patent glass carriers sliding on brass, pressed down by an stage and prisms, plane and concave mirror, on In two instances a fine adjustment. adjustable ivory pin. All have achromatic condensers, with tinted glass diaphragms, and all The stages have movable 5. Petrological microscope, rack and pinion coarse but two have iris diaphragms, those having the ordinary wheel instead. A national binocular, single-jointed arm. with cut Lister arm, and lever of the first order object holder, with glass plate inserted for the ivory point to work on. between fine adjustment screw and work. on graduated tripod plate. Body adjustments same Brass as in national binocular. Large best binocular stand, double pillar rotating and rotary stage. on single jointed arm. The other apparatus in this centring and focussing movements, holding Swift's Mechanical rectangular without mechanical rotating stage and finders, but of substage. case is as follows: 3 object glasses, 2 lamps, 2 ice-complete condenser, with iris diaphragm, selenites, 8. Large binocular, all bright, same as No. 7, movements to substage. Plane and concave mirror having in addition a substage, with mechanical Focussing and rectangular microtomes, staining fluids, etc. freezing microtomes, 1 ether freezing, and 2 ordinary polariscope, &c. a novel feature in this exhibition case, viz., that and patent fine adjustments; stage, rectangular, mechanical plain rotating; substage, mechanical rectangular and focussing mirrors as above. 6. Challenge binocular, rack and pinion coarse, Multum in parvo condenser containining dia7. The same, but with mechanical rotating stage, with finders. phragms, selenites, stops, polariscope, &c., in lieu Centring gear to stage. justment, multum in parvo condenser, packed in with even a rackwork coarse adjustment. By pay- which have been lent for use in the laboratory. I well remember, when I first turned my attening an exorbitant price I succeeded in getting a tion to students' microscopes, there was not one in this room, there are others by various makers, In addition to the microscopes exhibited in cases Among other things worthy of note are sterilisers by steam and dry air; microtomes, 1 ordinary, 2 condenser added. On asking why they did not microscope by Coppock, non-inclining, sliding rack and pinion coarse adjustment fitted on my in-cal coarse and fine adjustments, glass rotatfreezing by ice and salt, 3 by ether spray photo-make students' microscopes with these additions, I tube coarse, and direct strument. Subsequently, I had an achromatic ing stage, plane and concave mirror. A student's Two students' microscopes by Baker, mechaniscrew fine adjust is far away in their favour, whether used in a pipe Mr. Wenham's suggestion of bringing the levers If Mr. Wenham would kindly explain the general construction of his six-octave instrument it would be very interesting, as I have never seen so large a compass controlled by so narrow a strip of paper. Even my four octaves required a strip 18in. wide, and the organina strips are over five inches wide for only 16 notes. Possibly two separate strips, used simultaneously but acting on two sets of levers, one set for treble and the other for bass, might be found to answer. I suppose I am the correspondent referred to as having given the method of preparing the strips some three months ago. The mode alluded to by Mr. Wenham is no doubt that by which the barrels of organs are pricked off; but the instructions that I gave were simple and required no special appliances. As regards the time taken, I find an ordinary hymn tune such as "Aurelia" occupies me a long evening, but airs without chords are more quickly got Over. It would not be difficult to contrive a little apparatus by which the tune should be marked off as it was played on ordinary keys, but probably any one able to play the tune would not care to be able to grind it out mechanically afterwards. As regards "expression," casually mentioned by Mr. Wenham, I forgot to say that the organina has the usual shutter, by opening which the loudness (and harshness too!) is increased. I think a better way is to modify the air pressure by a separate line of perforations. lieve that any tuue can be played on the instru ment. With somebody who can blow properly and use the knee swell it leaves nothing to be desired, considering its simplicity and the almost impossibility of its getting out of order. The smaller instrument, melopean-organette, is, like the other, of McTammany's make, and has a set of tubes (or imitation tubes) over the holes, with a sliding shutter to produce swell effects. Unfortunately, could not get some of the reeds out to see their stamp, but there are 14 of them, and I believe they are like all the other organettes. The scale, so far as I can give it, is :-A (below mid C) BCDEF sh. I have no doubt some of your readers can fill the gap, but the last five are at the treble end. This instrument I find is quite loud enough; but, of course, it suffers from the defects pointed out by Mr. Wenham, which, however, are not much of defects to the majority of those who are likely to buy these instruments. The reeds are strong-made specially I believe-and are not the usual A. O. reeds thinned down, consequently the simplicity of the construction, taken with the strength, makes an instrument well adapted to its purposes. I wish I could persuade our worthy friend Mr. Wenham to give us a paper on this subject, with the sketches he cannot spare time to do just now. I think we will all be contented to await his leisure, if he will promise to do some time what no one, probably, can do better. Gray's Iaa. STANDARD INTERCHANGEABLE MANDRELS. [23014.]-IN continuation of my letter of June 6th (E. M.," No. 1002), I am now favoured by Mr. Hartley with a full-sized drawing of his interchangeable mandrel. ments. A microscope illustrating a hot stage, by Hawksley. A No. 2 stand by Powell and Lealand, the same as No. 1, without mechanical rotation to stage and finders, in. less of stage movement, and no fine adjustment to substage. A college microscope by Swift, same as No. 2 in their case. A Nelson-Swift microscope, with 10in. JacksonLister body, rack and pinion coarse, and patent fine adjustments, plain brass horseshoe stage, with finders, focussing and rectangular movements to substage, rotary stop carrier, plane and concave mirror on single-jointed arm. Zeiss dissecting microscope, with screw-focussing adjustment and hand-rests; triple combination lens, with concave eye-piece. Zeiss simple microscope, sliding tube coarse, and direct screw fine adjustments, plain stage. Zeiss large monocular microscope, rack and pinion coarse, and direct screw fine adjustments; body rotating round stage, stage plain. No substage, but with chromatic condenser on sliding frame, without centring movements, plane and concave mirror; rotating and rackwork traversing stop holder. This ends the account of the microscopical apparatus in the Biological Laboratory. In the Health Exhibition proper, we find in the French section the following apparatus by Duboscq-A vertical photo-micrographic instrument, with electric illuminating lamp. A spectroscope. A colour meter, which, by means of prisms, throws the colours of two objects into one eyepiece. A Sprengel's pump, with six falls of mercury. An inverted monocular microscope by Nachet for examining fluids. A photo-micrographic apparatus, with an eyepiece ingeniously inserted at right angles by means of a prism, to simplify the arrangement of the object ani light. This will save much time and labour, especially when the plate is placed at a considerable distance from the objectglass. A microscope by Verick, sliding tube coarse and direct screw fine adjustment, plain stage, ought, perhaps, to have explained in my letter concave mirror. Ditto, with rack and pinion of June 6th, that paragraphs 2 to 9 inclusive, which coarse, and direct screw fine adjustments, plain appear as extracts from Mr. Hartley's letters, are stage, condenser focussing by rack and pinion, not exactly Mr. Hartley's paragraphs. His letters without centring movements. Swing mirror, ditto, to me were not written for publication; they conditto, with mechanical motion to stage in one tained references to matters not connected with the direction, finder, and spectroscope. Student's study of this question of interchangeable mandrels, microscope, sliding tube coarse, and direct screw and the data were elicited, not always in natural fine adjustment, condenser without any mechanical sequence, in reply to letters which he kindly movements. Large monocular microscope, rack answered for my own personal information as a and pinion coarse, and direct acting screw fine brother member of the Amateur Mechanical Society. adjustments, draw tube, plain glass stage, focussing It was only afterwards that I asked for permission substage condenser, with diaphragm, no centring to publish portions of their contents, and he then movements, plane and concave swing mirror, kindly placed his letters at my discretion. In order, and object-glasses. Large inclined plane microtherefore, to present Mr. Hartley's data to the tone. Large argand gas lamp, blue chimney, and readers of the ENGLISH MECHANIC in fitting form, plano-convex condenser. Before passing on, it is I had to eliminate extraneous matters, to arrange worth remarking that among the Continental [23013.]-I BEG to assure "A. S. L.," p. 420, the topics in their natural sequence, and, occamicroscopes there is not a binocular, a complete that I had, previously to writing my letter, read sionally, to paraphrase Mr. Hartley's language. mechanical stage, or a substage to be seen. what he had already printed. I quite agree with Mr. Hartley writes me that in my letter there is Messrs. Watson and Son's case contains 18 micro-him as to what has been said with regard to the one mistake." This mistake, which may be of scopes, of which two are cheap folding, with rack-gradual advance of the holes over the tubes pro- importance as to Mr. Hartley's priority in certain work coarse adjustments only; six have rack work ducing a slight slurring effect; but I do not under-improvements of the geometric chuck, is due to the coarse, and small side lever fine adjustments, stand why in the instrument without levers the misplacement of a comma and to an ambiguity in plain and concave mirrors, glass stages; another holes in the paper need be twice the length of the one of Mr. Hartley's letters, which ambiguity I has a metal stage; another a mechanical stage; others. Unless "A. S. L." means some instruhave read in its unintended sense. I would coranother in bright brass; another, a larger size, ment of which I know nothing, I can assure him rect the mistake as follows:mechanical stage, small lever, fine adjustment; that he is mistaken about the organina being quite another, same size, binocular, without mechanical a new form, brought out last year, for it is one of stage. Petrological microscope, bright brass, several forms of lever machines, the earliest of coarse adjustment, graduated in inches, with which (of the present epoch) was patented here by vernier, non-mechanical, rotary stage, graduated, M. J. Matthews in 1878 (No. 2509), and in one dewith centring gear, prisms, and concave mirror on sign was illustrated in Vol. XXIX., p. 105. All arm, double pillar stand. Binocular in case, fold- these instruments were at first made with levers, as ing tripod, double pillar stand, swinging tail piece, were the German things, some of which preceded ordinary rotating non-mechanical stage, no sub- them; but it was soon discovered that levers were stage, small side lever, fine adjustment. Ditto, troublesome, and that the use of the exhaust bright brass, focussing substage with rectangular bellows facilitated the employment of the simple movements. Ditto, black brass, without substage. holes in the paper. It is simply because I know Monocular, bright brass, double pillar, swinging that fact, that I recommend readers of the ENGLISH tail-piece, no substage, plain rotating stage. Large MECHANIC, with an idea of making one of these inbinocular, all bright, top action, thin mechanical struments, to think twice before they adopt the stage, finders, ordinary rotation, graduated, lever pattern. There can, I suppose, be no doubt substage, focussing, with rectangular movements, body, cut Lister, with lever, fine adjustment. Objectives, 3, 2, 1, 1, 3, 1, fin. Nosepieces, double, treble, quadruple, and facility; lamp, condenser, &c. A novelty in this case' is the graduated scale and vernier on coarse adjustment of petrological microscope. July 12. Edward M. Nelson. AUTOMATIC MUSICAL INSTRUMENTS. [23012.]-I was glad to see Mr. Wenham's letter on p. 340, and thank him for his reference to the account of the organina. I can quite endorse Mr. Wenham's preference for the lever arrangement as regards promptness of speech of the reeds. The failure of the original instrument of 1848 was due to the drawling, dronelike effect produced by the perforated paper being used as the actual valve. This was in a pipe organ, and it was the superior quickness of speech of the free reed, combined with the fact of its pitch not being affected by the gradual admission and exclusion of the air, that suggested to me the construction of my first model (nearly 25 years ago) with reeds instead of pipes. Subsequently I tried levers, and the comparison Is the strip in the six-octave instrument drawn through by feed rollers? because the friction of 71 levers pressing on the paper would seem too great for the frictional grip of the indiarubber-covered rollers to overcome. In my larger instruments I tried discs with peculiarly-formed teeth catching in holes in the paper strips, but the paper is apt to get torn if the least hitch occurs. Probably the winding on to a roller is the simplest and best arrangement. A. S. L. that, from a musical point of view, the levers do Mr. After my describing the making of the compound geometric chuck and the adapters by which Mr. Hartley made it to run true upon the Norris 1.themandrel ("E. M." page 299), the fifth paragraph of my letter reads thus:-"My second compound geometric chuck, with three sun-and-planet motions, I sold in 1859 to Mr. George Plant," &c. Hartley now writes that, though this was his second compound geometric chuck with three sunand planet motions, it was the third compound geometric chuck which he had made, his first chuck having only two sun-and-planet motions. Mr. Hartley adds: "My second compound geometric chuck was constructed for James Wrigley, Esq., of Ashmeadows, Bury, Lancashire, formerly of the firm of James Wrigley and Son. Mr. Wrigley care to see the geometric chuck which Mr. Norris had purchased of me, and arranged for me to make him a like chuck. Afterwards, I asked Mr. Wrigley to allow me to make the chuck with three sun-andplanet motions, and to add any other improvements which I might devise, so as to make the chuck as perfect as possible. He replied, 'Make it as you like, and I will send my lathe up to your house for me and another for yourself. This offer I gladly you to use whilst you make a geometrical latbe for accepted, and, in 1849, I commenced to make for Mr. Wrigley a new lathe with a compound sliderest, and a compound geometric chuck with three sun-and-planet motions. The whole of it was made in my leisure hours. Mr. Wrigley was so interested in the construction and progress of the chuck, &c., that he spent hundreds of happy hours watching its progress. "In April, 1859, there was at Accrington an exhibition and bazaar for the building fund of a Sunday school. At that exhibition my geometric lathe with my third compound geometric chuck (the second with three sun-and-planet motions) was exhibited to thousands of visitors. I attended several times to work the lathe and show the peculiar motions of my compound geometric chuck. I ENGLISH MECHANIC AND WORLD OF SCIENCE: No 1,008. JULY 18, 1884. also cut several specimens of geometric turning, Mr. Hartley also writes: "I have had for upwards of a dozen years ready for publication a complete description of my geometric lathe, &c., with practical instructions for the guidance of those who may wish to make their own geometric turning apparatus, &c. work the lathe mandrel is fully described, and how In this to make one accurately, &c. The expense of the engravings has somewhat prevented its publication, for whenever it is published the whole shall be fully and well illustrated with accurate detail and sectional drawings. I have of late further improved the geometric chuck, whereby a new class of geometric figures can be produced, and which no other chuck can execute. illustrative specimens of geometric turning I intend The whole of the to be quite unique. The illustrations of the chuck will be executed by the Woodbury proCeRs. I am taking photographs of the various parts, so that they may be accurately and clearly illustrated. For some years also bold relief turning has engaged my attention, and I have been inventing and making new apparatus for this particular class of work. "One of the most important and vital points to be observed in making interchangeable chucks and mandrels is to turn the mandrel quite cylindrical, hole, which is drilled at right angles to it. Tais bearing-zone of the manire?-face be carefully and to be careful to turn the face side of its collar a true plane, so that the back part of the chucks may fit accurately against it; the threads also must be cut and chased quite true and finished whilst the therefore giving a mandrel face 1.75in. in diameter. "The shoulder is cylindrical, 375in. by 1-75, and mandrel is rotating in its own bearings. My The chuck body is 2in. in diameter, and rounded interchangeable mandrels are just as true when down at its base to a face of lin. The chuck face used in the lathe horizontally as when used verti- is turned up true by cutting tools, and no "scrapcally. I use them vertically sometimes, in order to ing up be better able to see the geometric figure cut, and is taken to see that the mandrel-face bearing lies in sometimes to enable me to polish and figure specula a plane at right angles to the mandrel axis. The or even polishing is allowed. Great care for telescopes. I do not claim any merit in making nozzle is 1-25in. in diameter and 1.75in. long, with my chucks interchangeable; but they are so, and it is useless for stubborn people to fall out with per inch, but leaving at the base of the nozzle a write upon these questions, and we all shall be a thread of Whitworth form making seven turns come into the arena. He is eminently qualified to facts. The lathe head, which I informed you had cylindrical portion of 25in. uncut by screwthread. grateful for his contributions. To the Darwinians I am glad to see that Mr. Wenham has again three mandrels, has movable long collars of a peculiar form for the two outside mandrels; these meter. The mandrels are only hardened at the from him, will be interesting. But this habit, The bearings are 2iu. long by 125in. in dia- also his habit of throwing mud at those who differ collars are in fact expanding mandrels. I have back end where they are in contact with the tail-while interesting as a fact for Darwinian observers, also a fourth mandrel, which I use for special pur-pin, which also is of cast steel." poses; but it is a lighter maudrel than the others. The four mandrels can all rotate at one time, and tation marks make a complete and faithful digest the position which we desire to assign to him. If ali at one speed, or at various speeds, according to of the data which I have gathered from Mr. Mr. Wenham could pardon my making him a The paragraphs which I have now given in quo- Wenham generally writes. And it derogates from does not help us in the subjects upon which Mr. The duty they are performing. collars can be used for carrying patterns and to give my own questions, and the paragraphs are to be the habit. But I ought not to make such a comThe movable Hartley. the expanding mandrels a lateral motion, &c." Some points have only been elicited by suggestion, I would say that he should now suppress After remarking that he should not have so as to put them into fitting shape for the readers enough to come out as a champion for the process taken as edited, condensed, and arranged by me ment at this moment, when Mr. Wenham is kind thought there was any difficulty in being vinced of the truth and general practicability" of in- comments, and the constructions by which he has face, and I can assure him that we all shall read 66 conterchangeable mandrels, Mr. Hartley adds, "Al- obtained his beautiful results, are curiously in ac- his arguments in favour of that process with much of the ENGLISH MECHANIC. Mr. Hartley's practical of scraping away the truth and flatness of the chuckthough I do know that it is difficult to obtain careful, accurate workmen, men who have heads, and who have already made. cord with the principles and suggestions which I interest. Mr. Wenbam says it is a precaution use them of my compound geometric chucks or the working courage to defend this "scraping up I never polish any part parts of any other turning apparatus, but finish that should always be seen to by whatever means them with cutting tools. This can easily be done port of it. The first reason is that the paragraph a chuck is fitted." by grinding the tools to suitable forms or angles, Hitherto no one has had the according to the peculiarities of the article which even Mr. Wenham only assigns two reasons in sup has to be operated upon. Turning tools should be process, and ground in a small slide rest to the proper angle, on which I commented was written 38 years and then touched up upon an oilstone, and the cutting edge angle very slightly rounded by a construction. curved sweep upon the oilstone. The cutting edge should be made to cut in the direction of the traverse of the tool, so as to avoid lateral pressure, jare, &c." can . Referring to the subjoined diagram, Mr. Hartley writes: question as this of interchangeable mandrels needs to be studied, we must proceed in one way if we Turning now to the method in which such a wish to arrive quickly at sound conclusions. Firstly, we must collect faithfully and define accurately all the facts which bear upon the subject. Then we study the principles which underlie the most successful of the constructions. Finally, we evolve, if possible, higher and better forms of of Mr. Hartley's mandrel, I must here stop to point out that the traversing movement of the Without entering upon criticism mandrel is indispensable for such of the higher co-ordinates, as well as for swash-turning, and for operations of geometric turning as involve three plans, Mr. Hartley's bearings are ineligible, as short screw cutting. If this principle governs our also is the back centre mandrel. But our first object is to collect the constructions and to study the practice of such eminent mechanics as Mr. Hartley. He will be as pleased to see his constructions criticised as we shall be to devise suggestions for their generalisation or improvement. ago, &c. But this does not convince me, because the paragraph in question happens to be no part of the classical volume to which he refers it, but was written by Holtzapffel the third, anno domini 1879, second reason is that it is a usual practice. This reminds me of the arguments which were used (vide Vol. IV. against the Reform Bill of 1832. pages 402-3). Mr. Wenham's Parliament to represent Old Sarum, which contained argued that the practice of electing two members of and, therefore, ought to be continued. But the It was then argument did not save the rotten boroughs, and it will not keep on its legs the "scraping up" process. only a public house and a pump, was a usual one," James Edmunds. Grafton-street, Bond-street. "I at all times prefer steps of hard brass stepastal to the cone necks, especially for small lathes. I have known one of Whitworth's 10in. centre Lathes worked constantly by one man for upwards of thirty years, and the brasses were not worn away the thickness of a piece of writing paper. The top brasses for such small and short journals as lathe mindrels should only be countersunk, they do not require a longitudinal groove at the top in order to obtaining careful, accurate workmen-men who diffuse the lubricant. Mr. Hartley's remarks as to "the difficulty of worked out of the journals, and runs down the it is as true of physicians, lawyers, and artists as of I inclose full-sized drawing of one of my best When grooved, the oil is have heads and can use them," is very true. But ORNAMENTAL TURNING. THE lathe head long before its lubricating properties are journeymen turners. What I had to show was traversing mandrels. STANDARD MANDREL. used up. Journals, when properly lubricated, d that, the teaching of our workmen on this matter ameter, and the nose is ths in diameter by the not touch their bearings, but rotate freely within has been wrong in principle. Until the mandrel- in length. The nose is screwed with a slightly [23015.]-AGREEABLY with Dr. Edmunds' request, the lubricant. The lubricant should be suitable to face is extended in diameter sufficiently to get truncated angular thread of 50 making 8.75 the diameter of the bearings, and to the length, over the unavoidable errors of workmanship we turns per inch. The base of the nose is uncut by The flange is 13in. in diweight, and power that has to be transmitted cannot depend upon eliminating what I have the thread, and is left full size. The angular through them. where lubrication has been neglec ed, or an unWear and tear only begins described as "angular variation" from the set thread of 50°, slightly truncated and just smoothed suitable lubricant is used. The screw F has a fine using only the outer zone of the mandrel-face for delicate-looking and beautiful thread, and at the thread of 20 turns per inch. It is used for setting the bearing of the chuck-face, we cannot avail same time very strong and durable. The enof our chucks. Until we adopt the principle of down, as produced by my Whitworth hob, is a up the top brass st p. its end up to the head, and there joining the cross tended radius in the mandrel-face. But unless the thread very well, and the termination of the thread It has a hole drilled from ourselves fully of the correcting action of an ex-graving does not show the true section of the screw |