or it may be carried in a special place cast for it on the rear jaw of the vise, as shown in the engraving. It can be readily turned back out of the way when not in use by simply loosening a screw, and without detaching it from the vice. In the case of a piece of work too large to be held in the vice, the machine can be clamped directly to the work itself. The standard and arms are of round section, and can be fixed in position to operate at any angle and on any piece of work that may be held in the vice. It is adjusted vertically by a screw as shown, and is fed back and forth over the work while the

cutter is revolved by the hand at the wheel shown on the right. Horizontal adjustment is accomplished by a threaded sleeve working in a split bearing which can be clamped to hold the cutter in any position without interfering with its free revolution. By substituting a drill chuck for the cutter it becomes a most efficient drilling machine, doing work that it is impossible to accomplish in a lathe or ordinary drilling machine. For cutting off bars, rods, &c., the milling wheel is replaced by a circular saw. This invention has been patented by E. E. Schermerhorn, of 125, West 53rd Street, New York.-Scientific American.

SCIENTIFIC

SOCIETIES.

ROYAL ASTRONOMICAL SOCIETY.
THE
HE March meeting of the Society was held on
the 14th inst. at Burlington House; Mr. E.
Dunkin, President, in the chair.

did an enormous amount of work in clearing up arrears of observations, reducing them and publishing them in a systematic form, in the 1840 to 1860. catalogues, but there remained a number of meridional observations made with the transit instrument and mural circle between 1849 and 1852. In the intervals of time which Mr. Stone could spare, he had commenced the reduction of Mr. Downing read a paper on "An Instance these observations, and I found the work of reducof Change of Personality in observing Position tion half finished when I arrived at the Cape. Angles of Double Stars, and on the Orbit of This work has been finished; the mere work of a Centauri." He had been attempting to determine reduction was, however, a trifle compared with the the orbit of a Centauri, and for this purpose had trouble of revision and comparison with other been comparing the observations of Dr. Elkin and catalogues, but I am happy to say the work is now Messrs. Hall, Ellery, Tebbutt, and Russell, in order completed and is in the hands of the Stationery to make Dr. Elkin's observations correspond with Office. It consists of over 4,300 stars, chiefly south those of the other observers. He had found that of the Equator, and it is reduced to the Equinox of the position angles computed from Dr. Elkin's ob- 1850. There is a matter in connection with this servations would require corrections of 7° for 1878 catalogue which is singularly à propos of Mr. and 3 for 1880. If the observations made at Common's paper just read. I have reduced all the Sydney were omitted, they would require corrections stars which are common to Mr. Stone's catalogue of 1° for 1878 and 11 for 1880. Mr. Russell's posi- of 1860 back to 1850, and find that at the Equator ion angles agreed fairly well with the mean of the and at the Pole both the catalogues are practically other observations up to the end of 1877; then dis-identical; but from the Equator to the Pole there is a cordances of 5 to 6 appeared in 1878, 4° to 5° in regular curve of error in Right Ascension. It is reduced 1879, 1880, and 1881. This indicated some change to a second of arc at the Equator,and at about 10° from in Mr. Russell's method of observation. The errors the zenith, the difference is no less than 8" of arc. appeared to depend on the inclination which the I should be sorry to express a definite o inion on line joining the stars made to the vertical. the subject, but in 1850, when reversible instruMr. Gill said that he had been working with Dr. ments were employed both at the Cape and at Elkin on the observations of a Centauri. Dr. Greenwich, there is practically no difference between Elkin was preparing a tolerably exhaustive work the Cape and Greenwich Catalogues; but in 1860, on the orbit of that star, in which all when a non-reversible instrument was employed at the observations which he could collect had the Cape, there was this great difference: We are been discussed. He had made a graphic now carrying out a series of observations in which representation of the observations, showing those of the same star is observed direct and by reflection, different observers in different colours, and no one in order to test whether the error can be due to could fail to be struck with the extraordinarily flexure, and I hope to have collimators erected at large systematic errors of the different observers different altitudes further to test the matter. Soon which appeared to be connected with the inclination after my arrival at the Cape I received from Proof the line joining the two stars to the vertical. fessor Newcomb a letter requesting that a series of The different observations made even by the same observations of occultations of stars by the moon observer at different times accord so badly with might be made in the southern hemisphere. I reone another, and with any assumption that could plied that I should be happy to undertake the be made as to the stars moving in an elliptic orbit, work if Her Majesty's Government would conas in some cases, to give rise to the idea that sent to provide predictions of the occultations. a Centauri could not be moving according to the laws These have been made at the Nautical Almanac of gravitation. This was the case with Jacob's office in London, and an immense number of such observations, as well as with those of the observers occultations have been observed at the Cape. I mentioned by Mr. Dowing: but a comparison of have also collected from amongst the records of the all the observations gives a fairly good elliptic orbit. Cape Observatory between 400 and 500 occultations, We have several hundreds of observations of which have been observed by my predecessors and a Centauri made at the Cape, which have not yet have not been published. When I was at Strasbeen printed. bourg in 1879, before going to the Cape, I met a Mr. Common read a paper entitled "Suggestions young student, Dr. Elkin, a pupil of Prof. for Improvements in the Construction of Large Winnecke, who was engaged in writing a memoir Transit Circles." He thought that the chief defects on the parallax of a Centauri. He requested meto in the present form of large transit instruments arose send him observations made at the Cape of that from their being made upon the same pattern as star. I told him I had acquired by purchase Lord metal. The axis of the instrument usually con-mounted equatorially at the Cape to carry on the smaller instruments, but with a larger weight of Lindsay's heliometer, and intended to have it sists of two hollow cones of metal joined in the work of stellar parallax. The matter seemed to centre by a hollow cube through which the tube of fire his enthusiasm, and he expressed a great the instrument passes. He proposed that the axis desire to go with me and share my work. I should be made in the shape of a girder intended to said I could not offer him a position, and he resist flexure. The tube of the in-trument is to be said he did not want one; so entirely done away with, and the object-glass and eyepiece to be supported between two circular discs of metal kept apart by masses of metal symmetrically placed with respect to the axis of the instrument, the curvature of the axis caused by the weight of the instrument to be as far as possible got rid of by relieving the weight by means of floats in troughs of mercury.

The Remarkable Sunsets.-At a recent meeting of the French Academy of Sciences M. Angot drew attention to the fact that in 1831 a series of striking twilights was observed extending over a considerable part of the year, and M. Tissandier, the well-known aeronaut, now points out that during the first days of July in 1831 there was a volcanic erruption in the Sicilian Sea, between the coasts of Sciacca and the Ireland of Pantellaria. A new island (Julia), which subsequently disappeared, rose from the bosom of the sea together with an upshot of ashes and cinders. M. Constant Prévost was sent by the Academy of Sciences to study the new formation. Prince Pignatelli assured him that during the early days of the eruption, the The Astronomer Royal said: one of the chief 10th and 11th of July, a fiery column arose from difficulties which arise with the present form of the crater "like a bouquet of artificial fire." At the transit instrument, is, that holes have to be the beginning of August an immense column of made in the cube for the purpose of illuminating dust rose and emitted a bright light. On the 5th of August "an impalpable dust carried by the the wires, and this tends to weaken the cube; but winds fell in abundance." The eruption lasted with Mr. Common's instrument there is no tube, several months, and the coloured sunsets of 1831 and the object-glass and wires can be attached to began about the beginning of August, soon after any part of the discs, so that the instrument would the commencement of the volcanic effects. The partake partly of the principle of the mural circle. Mr. Stone said, that as far as his experience went peculiar twilights were remarked at Odessa, Rome, the most serious difficulty that arose was not from Madrid, and in Germany-that is to say, over a the flexure of the tube and axis, but from the considerable area. shifting of the object-glass in its cell; certainly, Bleaching Shellac.-M. Ande gives the follow-that was the chief defect of the transit circle at the ing method:-Three and a quarter pounds of soda Cape, and also of the transit circle at Oxford. are dissolved in nine and a half gallons of water There might also be a flexure or slipping in the contained in a small boiler or kettle. Eleven pounds screw where the cell of the object-glass was screwed of crude shellac are added in small quantities at a on to the tube. He thought that Mr. Common's time, giving a turbid solution possessing the method of relieving the weight from near the characteristic odour of shellac and a violet-red centre of the axis by floats in the mercury was a colour. The liquid is boiled for a few minutes, and, step in the right direction. while hot, a wooden air-tight cover is cemented on Mr. Gill said that some of the German makers the vessel. When the liquid is quite cold the cover had already placed friction wheels so as to relieve is removed, and the thin cake of fat which is found the weight near the centre of the axis, instead of on the surface is separated. The solution is filtered close to the pivots as in English instruments. He through linen, the clear filtrate slowly decomposed could not fairly criticise the paper without having with dilute sulphuric acid, and the resulting pre-a further opportunity of examining Mr. Common's cipitate washed with water till no acid reaction remains. The washed resin is now pressed and melted in boiling water, when it can be shaped with the fingers. This shellac is cooled in, water containing glycerol, and, when hard, is dried. This shellac forms yellowish-white, glistening tufts which, when dry, are yellowish-brown. It should entirely dissolve in alcohol.

plans; but it was evident that many of his sugges-
tions were in the right direction.

A vote of thanks was passed to Mr. Common for
his paper, and Mr. Gill was called upon to give
some account of his work at the Cape Observatory.
He said: Our work has been of two kinds, first,
the reduction of old observations, and, secondly,
new investigations. My predecessor, Mr. Stone,

asked him

to come as my guest and live with me.
He accepted my invitation, and we have undertaken
a considerable amount of work together. We have
observed a number of the brighter stars which were
known to have large parallaxes, and have selected
smaller stars in their neighbourhood, nearly in the
major axis of the parallactic ellipse. We take them
as nearly as we can at equal distances on each side
of the larger star, but we are limited by our instru-
ment to a distance of 2°. Some times we cannot
secure that the three stars shall be exactly in a
straight line, and they may differ as much as 10° or
15° from the straight line; but we are anxious that
the smaller stars shall be at nearly equal distances
from the large star, and nearly equal in magnitude.
We then place in front of the segment of the object
the brighter star is
glass, through which
observed, a screen of wire gauze consisting of
one, two, three, or four folds, according to the
brightness of the star till we have made a
screen (sometimes of muslin, sometimes of wire
gauze, and sometimes of a combination of both),
which makes them appear precisely the same
magnitude. The two stars-that is, the large one
dimmed down by the screen, and the smaller one-
are then made to move over one another; there is
little difficulty in causing the two star-discs, which
each appear about a second in diameter, to pass
through one another with an accuracy approaching
to one-tenth of the diameter of the discs, so that
the probable error of each observation should be
about one-tenth of a second, though the distance
of the two stars may be 6,000 seconds. If there is
any error in the scale value produced by tempera-
ture or some other cause, it would show itself
equally in measuring the distance of the star on the
opposite side, so that when the distances are equal,
such scale errors may be neglected. Dr. Elkin has
now accepted the charge of the great heliometer at
Yale College, and is willing to continue the work
along with me. It is a work which will occup
about ten years, and I hope I shall be provided
the liberality of the Government with a prop

heliometer for the purpose. It must be an instrument of at least 7in. in aperture.

A number of papers were then taken as read.

QUEKETT MICROSCOPICAL CLUB.
MR.
R. EDWARD M. NELSON gave a demon-
stration on the 14th inst. at the above club
"On the Selection and Use of Microscopical Appa-
ratus," of which we give a résumé.

except in adjusting the correction collar in testing tion gave but a small disc of clear light; he had objectives. With reference to the question of the therefore engaged Messrs. Swift to construct a conrelation of aperture to power, he alluded to a note denser for the lamp on the Herschelian form, already communicated to the Club in which he had consisting of a meniscus and a bi-convex, which said, that by experiment he found that the normal gave a much larger and clearer disc of light, as eye was capable of defining objects at a distance of shown by diagram. He did not advise the use of 10in., making an angle of 1' 23", that is to say, it the bull's-eye for direct transmitted light; it was was capable of separating lines ruled at the rate of preferable to point the microscope direct to the 250 to the inch. Applying this to microscopical flame, or to use the plane mirror. The bull's-eye Ivision with a half-inch, the question was-What was useful for oblique light, especially when a Commencing with the choice of a microscope aperture was necessary to enable it to resolve any double-slot diaphragm was required. It was very stand, Mr. Nelson said the different forms of stands thing that would be brought to that visual angle by important for dark-ground illumination, and with might be broadly divided into two classes: (1) an amplification of ten times its initial power? the Lieberkühn. Oblique light with single-slot those in which the optical body was supported on a For example: the half-inch having an initial power diaphragm he obtained better without bull's-eye. In bar or arm projecting at right angles from the of twenty, with a lin. eyepiece would magnify 200 treating of the use of condensers, he could not too pillar-rack, as in Powell and Lealand's; and (2) diameters; multiplying the last figure by 250, we strongly dwell upon the importance of prothose known as the Jackson-Lister, in which the obtained the product 50,000; an aperture of 63° portioning their aperture and power to those of the optical body had the rackwork applied directly to would be required for the resolution of lines of that objectives. In his judgment no condenser had yet it and supported by a limb (two such microscopes, fineness. He might warn microscopists generally of been devised so effective as Powell and Lealand's for by Swift and Son, were shown as examples). His the immense number of grossly defective eyepieces all powers beyond. It had an aperture of about 170°, own experience was decidedly in favour of the that were offered for sale. The Huyghenian eye- and a focus long enough to go through any ordinary Powell form, as lending itself so perfectly to the piece should be constructed so that the radius slip, and was provided with a beautifully centred application of the best system of fine adjustment of curvature of eyeglass to the field-glass disc of graduated diaphragms, and with slots and that he knew of the long lever acted upon by a should be as 3: 1. Certain manufacturing central stops of admirable construction. Whilst fine screw. Moreover, this form, when properly opticians had entirely lost sight of the formula, and giving it the palm over every other form of achromade, allowed the complete rotation of the stage, they made the same field-glass do duty for eye-matic condenser, he was alive to the fact of its being and plenty of space for manipulations on the stage. glasses of different foci. The result was lament costly. It was so well made that it must be costly. The Jackson-Lister might possess an element of able. Well-made eyepieces were most essential to Its convenience was so great that he could hardly steadiness beyond the Powell for use on board good work with the microscope. Here, again, he suppose that anyone who had once gained exship (as stated by Dr. Carpenter), but he could could bear testimony to the conscientious accuracy perience of its utility would consent to use high not regard that point as very essential, and it cer- of Messrs. Powell and Lealand, who had not de- powers without it. He regarded it as the most tainly did not compensate for the disadvant-parted from the strict Huyghenian formula for eye- useful apparatus in his collection. Messrs. Swift ages which he feared were insuperable in that pieces. On the use of daylight, he said he found have produced a condenser of about 145° aperture, model. The application of a good fine adjustment it effective for low powers up to in., and with con- which, by removing the front lens, could be reto the Jackson-Lister presented great difficulties. denser up to in. The direct sunlight involved the duced to a much lower aperture suitable for low He might at once state his conviction that the fine- use of a heliostat, otherwise the continued adjust-powers; it had a pivoted disc to carry the disadjustment attached to the body-tube-the short ment of the mirror was irksome. Where strong phragms. The microscopist should possess both lever acted upon by a screw-was" radically bad." resolving power was needed, oblique pencils of these condensers to enable him to do critical work He considered Messrs. Swift had hit upon a system sunlight from the heliostat would outrival any with high and low powers. With Messrs. Swift's of fine-adjustment for the Jackson-Lister that was, other illumination; but much care was necessary condenser it was advisable to have an adapter to fit at any rate, far better than the short lever; they not to injure the sight, and, on the whole, he could beneath and carry three concentric rotating rings, had applied a long lever vertically behind the body-not recommend its general use except for photo- which were specially convenient for experimenting tube, acted upon by a screw at the side, and thus graphing. Diffused daylight was too uncertain with central stops, or for zonal illumination. The attained an approximation to the certainty and too variable-for accurate testing of objectives. It superposition of two or three discs differently cut delicacy of the Powell fine-adjustment. The was not possible to get with diffused daylight the gave a great range of effects of light. They Jackson-Lister ought to be a far less costly instru- absolutely best image that an objective would pro- might also be used for selenites and mica, and ment than the Powell, as machine-work could be duce. A really critical image could only be seen would be found of great service in this combinaemployed largely in its manufacture. For the most with artificial light, and with a good condenser tion. He entirely condemned the use of paradifficult class of work he gave the preference, with- and diaphragms. He did not mean to say boloids for dark-ground illumination. Properly out reserve, to the Powell model; it must, however, that no good werk could be done with diffused adjusted central stops with the condenser would be thoroughly well made, and must necessarily be a daylight, for excellent work was done with give by far the best dark-ground illumination. For costly stand. He could not regard any microscope low or medium powers; but he insisted opaque objects he thought nothing had been devised as worthy to be called a scientific instrument unless that it was not possible to do any such critical work so good as Lieberkühns, and objects ought as it were provided with a centring substage, as testing objectives by daylight as thoroughly as far as practicable to be mounted for use with and, indeed, he must emphatically urge that it could be done by artificial light. With daylight Lieberkühns, and not covered up with paper. If scientific microscopy really began with the use and mirror only there was milkiness, and what he the side illuminator were used it should be attached of a substage condenser of which he would might term "glaze." The milkiness could be got to a fixed part of the stand, not to the body-tube speak later on. Regarding the choice of objec- rid of by a diaphragm, and the "glaze" by using or stage. The vertical illuminator was a difficult tives: they should be selected so that the battery a ground-glass behind the object. Unless a con- apparatus to manipulate, and required great might be increased without having to exchange, denser were used there would always be found a patience. It afforded a remarkable proof of the and without useless expenditure. The beginner falling off of the quality of the image with all existence of aperture beyond the dry-lens limit. might have a lin., and a ; later on a might be powers higher than . From long experience in He exhibited a diagram of the back lens of a soil added, and as a higher power a oil-immersion working with the microscope, he felt justified in immersion objective of 1-43 N.A. when used with of 1.43 N.A., such as Mr. Powell made so suc- asserting that on the whole daylight was more the vertical illuminator; the outer zone represented cessfully. For all working purposes the battery trying to the sight than lamp-light. Everyone the aperture beyond 10 N.A. The first requirewould then be complete, and the microscopist would understand the importance of keeping off ment with the vertical illuminator was to find an equipped to repeat any results hitherto obtained. stray light from the stage, &c. An ordinary object in close adherence to the cover glass, for it As luxuries a 3 inch,, and might be paraffin lamp having a wick of half an inch would was only such an object that lent itself to that got. It sometimes happened that the high initial answer most purposes admirably, and with low method of illumination. He was afraid he could magnifying power of the enabled the observer powers ground-glass should be employed either not say anything useful on that matter unless supto find some hitherto unknown object, or portion with or without condenser. The image of the flame ported by the microscope; but he had repeatedly of an object, more easily than with the; but could be projected in the ground-glass, nearer or exhibited the apparatus at the club, and therefore when once found its details of structure would further from the object. The oxy-hydrogen light he would not then dwell further upon it. be better made out with the. So far it had not might be serviceable for resolving such tests as camera lucida, he had been satisfied with Beale's been possible to construct aas perfectly as a , Nobert's lines. The incandescent lamp he regarded neutral tint reflector. On the use of the eyepiece nor with so high an aperture; hence it would rarely as entirely a failure for microscopical purposes. screw-micrometer, he said that for delicate bear any eyepiece beyond the lowest. The, how-This was at once obvious upon the consideration measurements it should be mounted on a separate ever, with proper manipulation, would bear the lin. that the finest images seen are got by viewing ob- stand not to touch the microscope, in that way he eyepiece, and then reveal structure that could not jects, as it were, in the image of the source of light. had repeatedly counted 90--100 lines in the whole be made out with ths as hitherto constructed. All critical images of transparent objects viewed by space of an inch. As to polarisation, he had Half-inch objectives had been made with apertures direct transmitted light required first that the so little time left that he must be content with the of 80°. Some authorities had declared that 40° was source of light should be pictured by the condenser simple recommendation of polarisers with large the highest aperture that could be usefully employed exactly in the plane of the object, the object then field. He might, however, remark that many with that focal length. He had obtained one of the best served to interrupt the image of the source of light. minute objects gave curious effects of polarisationexamples of the in. of 80°, and had made a careful The observer had simply to arrange the lamp, con- for instance, the Podura scale-and many of these series oftrials with it. He had applied diaphragms denser, and diaphragms so as to produce the most yielded most beautiful pictures when viewed with above the back combination to cut down the aperture perfect image of the source of light of the required polarised light. He then referred to the diffraction to 60° and 40° respectively, and the results might size in the plane of the object, the objective would appearances presented at the back of objectives in be briefly told. Taking the proboscis of the Blow-fly then have fair play. The size of the image of the viewing A. pellucida by axial light and again by and viewing it with the in. diaphragmed down to lamp flame could be controlled by distancing the oblique light, using, in both cases, dry and immer40° aperture, and arranging the illumination in the lamp, as illustrated by a diagram. There really was sion condensers. He also showed by diagrams the most favourable manner, he noted every detail of no other secret in the matter. With the incandescent progressive interpretations that had been made of the picture, the sharpness and blackness of the points lamp the image produced by the condenser repre- the structure of P. angulatum and P. formosum of the bristles, the transparency and clearness and sented the mere carbon thread, on which during the past 50 years, and concluded by some general precision of the image; then removing the no object could be seen projected; in order general observations on the difficulties of interpretdiaphragm behind the lens, he increased the aper- to obtain some extent of brightly luminous ing the images presented by microscopic objects ture to 60°, and he found the image improved in field, the condenser must be put out of requiring high magnification." every way. Increasing the aperture to the fullest focus, then the intensity of the light was so At the close of the demonstration Mr. Nelson extent, 80°, gave no advance upon the quality of reduced that the observer would simply discard the exbibited the various appliances he had commented image seen with 60° up to the lin. eyepiece; for incandescence, finding it far less serviceable than upon. Amongst them were Powell and Lealand's this reason he concluded that 60° was the really a shilling paraffin lamp. He had himself suggested No. 1 stand, with achromatic condenser, polariser, useful aperture for a half-inch, and gave as much the construction of a lamp for use with the micro-analyser, Huyghenian eyepieces, Kellner ditto, resolving power as the eye could well sustain with scope in which the flame could be brought very Swift and Son's large Jackson-Lister microscope, that combined power. No doubt the extra 20 low down near the table. The glass of the chimney with new fine-adjustment, and a small model of would give the lens a higher resolving power with consisted of an ordinary 3 by I slip, and so could the same fitted with condenser and diaphragm a stronger eyepiece, but he thought that might be be cleaned or replaced readily. The chimney was carrier as suggested by Mr. Nelson, objectives by better obtained with a lens of shorter focal length. of metal, and he preferred it black inside; he Powell and Leland, Spencer, and Ross, vertical In the matter of eyepieces, so far he had not done wanted the image of the flame on a black back-illuminator, Beale's neutral tint reflector, Abbe's useful work with anything higher than the one-inch, ground. The bull's-eye of the ordinary construc-condenser, &c.

As a

THE death is announced of Dr. Behm, the

editor of Petermann's Mittheilungen.

A practical test of the value of the phonograph LETTERS TO THE EDITOR. will be made by Dr. Zintgraff, who is about to travel in the interior of Africa. He will use the

instrument to obtain foil phonograms of the
speech and melodies of the natives, and trans-
mitting these to Berlin, they will, if possible,
reproduce the sounds on an exactly similar
instrument.

Dr. George Engelmann, one of the oldest botanists in America, and a fellow-student with Agassiz, died recently at the age of seventy-five. Dr. A. B. Griffiths, writing on the influence M. Faye recently presented to the French Academy of Sciences some drawings of Comet of certain rays of the spectrum on the growth of Pons-Brooks, made by M. Trépied at Algiers, plants in the Journal of the Chemical Society, and took occasion to point out that the changes expresses the opinion that the rays near the least in brightness which have occasioned some sur- refrangible part are the most active, that there prise were probably due to a rapid change is a connection between chlorophyll and iron, in the point of view of the comet as observed and that if iron is given it acts within limits as from the earth. The hypothesis is to be ex-food of great value. An artificial manure complained by some diagrams in a number of Comptes pounded of powdered anthracite and sulphate of iron has long enjoyed a good reputation.

Rendus.

M. Pasteur and his collaborateurs have anWe have received a copy of the reprint from the Memoirs of the Royal Astronomical Society, nounced to the Academy of Sciences the fact of Mr. Burnham's Double Star Observations, that by inoculation they can render all dogs made in 1879 and 1880, with the Dearborn 18 in. absolutely proof against the effects of rabies, in refractor. In some form or another, every double-whatever way or quantity the virus may be administered. star observer must have these lists and measures, and we presume those who are not Fellows of the Society can obtain copies at the apartments of the Society, Burlington House. The price is not stated.

a

The Microscopical Bulletin and Opticians' Cir; cular is a useful little "bi-monthly," published by J. W. Queen and Co., of Philadelphia. Partly a trade circular, it contains several notes which may be of value to many microscopists. The price is 25 cents per annum.

There are 67 candidates this session for the honour of admission to the Royal Society. Mr. Crookes will, it appears, not be able to undertake one of the lectures at the meeting of the British Association, and his place will be filled by Prof. Grylls Adams. A subsidy of 14,000 dols. has been awarded to assist in paying the expenses of the members, or rather of those who avail themselves of the offer.

[We do not hold ourselves responsible for the opinions of our correspondents. The Editor respectfully requests that all communications should be drawn up as briefly as possible.] All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 81, Tavistock-street, Covent-garden, All Cheques and Post-office Orders to be made payable to J. PASSMORE EDWARDS.

W.0.

In order to facilitate reference, Correspondents, when speaking of any letter previously inserted, will oblige by mentioning the number of the Letter, as well as the page on which it appears.

"I would have everyone write what he knows, and as much as he knows, but no more; and that not in this only, but in all other subjects: For such a person may have some particular knowledge and experience of the nature of such a person or such a fountain, that as to other things, knows no more than what everybody does, and yet, to keep a clutter with this little pittance of his, will undertake to write the whole body of physicks; a vice from whence great inconveniences derive their original." -Montaigne's Essays.

THE ARCHIMEDES CLEFTS-CLEFTS E. OF BIRT -CLEFTS ON THE S.E. OF MARE HUMORUM-THE CAVENDISH RILLS -HEVELIUS, COPERNICUS, JULIUS CÆSAR.

SELENOGRAPHICAL

As to these

On Saturday evening Mr. Clement E. Stretton, C.E., read a paper at Leicester on "Locomotives and Rolling Stock," giving a concise account of the leading dimensions and designs adopted by [22480.]-I HAVE, as opportunities offered, comWe have received the abstract of the Proceed-the various companies. The details were clearly interesting observations, and the following is a ings of the Liverpool Astronomical Society for explained by means of numerous large-size dia-pared with the moon some of Mr. Elger's very résumé of what I have found:Air middling. the fifth meeting of the session. It contains grams and several working models. February 4th, 1884, 9h. p.m. chart of the radiants of November meteors in Some of our beekeepers may be interested in a Musca and Taurus, and reports of the papers novel experiment in bee culture made by Mr. Highest power 165. Mr. Elger's drawing of the William Walker, manufacturer, West Burnside, Archimedes clefts before me (ENGLISH MECHANIC, read, as briefly noticed in No. for Feb. 29. No. 967, p. 106). I took his mountain c, cleft 6, Laurencekirk, N.B. That gentleman, having informed himself as to the Swiss mode of bee and crater d as my starting point of comparison, as these objects were easily seen. wintering, about the 1st of October last covered objects, I found crater d to be composed of two up eight hives of bees in two rows, first with a confluent craters elongated in the direction of the layer of straw about 6in. in depth, on the top of cleft. Mountain e is composed at least of two, that 6in. to 8in. of earth, and covered the whole between which the cleft runs, which was seen as over with roofing tiles. They were allowed to reaching in a straight line the foot of the Apenremain in this position till a few days ago, when nines through a flat region. Now, on the N.W. of they were disinterred. Five of the hives were, there is a chief mountain from the S.E. foot of in a healthy and lively state, and on Tuesday which emerges a cleft called x by Mr. Elger, but week were out working. The other three had suc- which I take for x, and which I have always seen up to it. Then on the S.E. side of e, 6 and d, there cumbed. One of them had evidently been de- as running about half way to Archimedes, and not stroyed by mice; the other two were very weakly is cleft 1 of Mr. Elger, but which I take as x, and when earthed up. Mr. Walker says they have which I saw running only from cleft A, close to the lost very little in weight since they were im- Archimedes projection. This cleft has a branch x mured in their winter quarters. pointing to Aristillus. About the middle of x (1 of The Scottish Meteorological Society's scientific Elger) and at a short distance on the S.E., there is a mountain which I have called 8, from which marine station at Granton was, on Saturday, emerges another cleft x, running parallel with x successfully launched from the ship-building towards Archimedes. Between x and x2, fronting yard of Messrs. Allan and Co., Granton, and branch x', there are, at least, two craterlets. Easttowed round into the adjoining submerged ward of all this another short cleft was seen, which quarry, where it was afterwards moored in posi-I have marked x, running from a crater to a tion. The barge upon which the laboratory is mountain near Archimedes. Compared with the built has a total length of 73ft., with 14ft. beam, direction of the other clefts, x inclines towards and draws somewhere about a couple of feet of the S. Parallel with x, x', 6 and x is a formation The Gresham lectures will be delivered in the water. The house in which the scientists will which I think I had not noticed before. It runs following order: Physic (Dr. Symes Thomp-work is 344ft. in length, and, taking up the from the N.W. side of the mountain, which Mr. Elger shows near his letter A on the S., and stretches son), March 25, 26, 27, and 28; Geometry (Dean entire breadth of the craft, is divided into two to a crater towards the S.E. At first it looks like Cowie), April 1, 2, 3, and 4; Divinity (Dean compartments, the larger of which is 20ft. long. a doubtful cleft; but on better examination, it seems Burgon), April 22, 23, 24, and 25; Law (Dr. In the sternward, or smaller room, which is set to be a succession of hillocks, or, perhaps, minute Abdy), April 29, 30, and May 1 and 2; Astro- apart for microscopic work, there is accommo- craterlets, and gives the impression of an interior nomy (Rev. E. Ledger), May 6, 7, 8, and 9: dation sufficient to enable four men to carry on force trying to burst the surface of the moon, but sucRhetoric (Mr. J. E. Nixon), May 13, 14, 15, and operations, and the larger is intended for biolo- ceeding only to raise it at short intervals. Something 16; and Music (Dr. Henry Wylde), May 19, 20, gical experiments and aquaria. Perhaps the of this kind will be seen at the W. extremity of the 21, and 23. The lecture begins each evening at most interesting feature in the furnishings of Descartes cleft. The above, with A, were all the six o'clock. this outer chamber consists in the laboratory clefts I could see during this observation. The fittings which went round the world in the difference between what I saw and Mr. Elger's Challenger, and which have been presented to sketch may be accounted for in part by the fact of sunset. Then the power I used was only 165 the station by Mr. J. Y. Buchanan, chemist and my observing at sunrise, whilst Mr. E. observed at physicist to that expedition. The water for the against 350. This region needs more study, and it aquaria is obtained from an overhead tank, sup- would be well to give as many other details as The Photographic Society is now in a position plied by means of a force pump. The extreme possible, as a help towards identifying the cleft. to exhibit to apparatus makers the standard after part of the barge is fitted up for the accom screws and gauges adopted by the society. Ap-modation of the keeper, and in the bow there is storage for dredging gear, &c. The steam 30-ton plication should be made to the secretary. yacht for the use of the station, which is now being built on the Clyde, is expected to be launched on the 26th inst.; and it is anticipated that about the 10th of next month Prof. Häckel, of Jena, will declare the station open for scientific work.

Prof. Sir Richard Owen was, on Saturday last, presented with an address by his fellow members of the Geologists' Association, and in reply said he should value it as amongst his chiefest treasures, and would hand it down to his son and grandchildren, some of the latter of whom may be moved thereby to follow in their grandfather's steps and become naturalists.

The Linnean Society has elected as an honorary associate Mr. W. Hodgson, a schoolmaster of Watermitlock, Penrith, author of a Flora of Ullswater, and well known for his extensive acquaintance with the Border plants.

If it is true, as Dr. T. Stevenson asserts in Guy's Hospital Reports, that water does, under certain conditions, act energetically upon zinc and galvanised iron, a simple test for the presence of zinc will be useful. Dr. Stevenson adds to the clear water, slightly acidulated with hydrochloric acid, a little ferrocyanide of potassium (yellow prussiate), when, if zinc is present, a whitish cloud immediately forms.

THE first International Congress of Ornithologists, under the patronage of the Crown Prince, will be An early human skull has been found at held at Vienna from the 7th till the 14th of April next. The programme proposed is as follows:-1, Podhaba, near Prague. It was discovered in a bed of chalk from which the tusk of a mam-Project of an International Law for the Protection of Birds; 2, On the Descent of the Domestic Fowl, moth had been dug out a few days previously; and the Steps to be taken in general for the ImIt resembles the Neanderthal skull, but its facial provement of Poultry Breeding; 3, Suggestions for angle is lower. The characteristics are ex- the Establishment of a Network of Stations for tremely low forehead and excessive development Ornithological Observations over the Habitable Globe. of the ridges.

Clefts E. of Birt.-It is very singular that "M. A." (ENGLISH MECHANIC, No. 982, p. 427) saw cleft 0 and not cleft, which is so easy as to be seen almost at every lunation. I have not yet seen cleft myself. In Mr. Elger's sketch (ENGLISH MECHANIC, No. 985, p. 496), a marking is given, like a cleft, running from Birt to the S.E., and nearly reaching the ridge he shows. I saw this object for the first time on March 26, 1874, and

several times afterwards. The two sketches I have bring this object as far as the 13° of E. longitude. I have always taken it as a very delicate cleft, and at times I thought I could see faint traces, here and there, of its connection with the Pitatus cleft on the N. of its floor.

Clefts on the E. side of Mare Humorum.-Ou March 8, 1884, the air being clear, though fluttering, I identified all the clefts given by Mr. Elger (ENGLISH MECHANIC, No. 970, p. 171), except 0, 1, which he notes as very which I could not see. Been without much difficultydelicate, was power about 100, single lens. The bay on the S. impressed me as having a low border. During this

122481.]-DR. KLEIN, of Cologne, drew attention about two years ago, in Petermann's Mittheilungen, to certain small dark patches found here and there in disturbed parts of the moon's surface, surrounding minute crater-cones. He considers the latter to be true volcanic vents, while the dusky or smokygrey areas on which they stand represent the lava or other substances which have emanated from them. One of the most noteworthy instances to which he refers is a well-marked dark spot on the floor of Alphonsus, marked p in Neison's Map XIII. The accompanying sketch, made on 5th March, from 7h. to Sh. Som., with a power of 384, shows the principal fostures which were then visible on and about the region in question. The dark area, p, extended up to the foot of the wall of Alphonsus, and was bounded on the S. W. and N.W. by slightly curved sides. It included two objects resembling small hills or crater-cones (the more westerly of the two being the larger, and casting

a pronounced shadow), which stand opposite the
end of a wide valley that cuts through the N.E.
wall of Alphonsus, which valley, though very ac-
curately drawn by Boor and Madler, is not shown
by Neison. A little to the N.W. of patch p is an
obscure and delicate craterlet, m, connected with
the wall by a ridge, as shown by the shading.
Adjoining p on the S. W. is a lighter area,
bounded by a ridge, h, k. A cleft, 2, traced from
a craterlet on the wall of Alphonsus, runs nearly
parallel to the wall up to this ridge, where it widens
into a spindle-shaped depression, which appears to
be crossed by the ridge, and then to extend for some
Another cleft, 1, parallel
distance on the area s.
to 2, stops at the ridge. 3 and 4 are shallow de-
The study of these interesting objects ought to
pressions on the floor of Alphonsus. On 4th
February, 6h. 30m. to 8h. Om., the E. wall of Al- commend itself to every one interested in seleno-
phonsus being on the terminator, most of the fea-graphy, as it is a beazole of lunar research which, if
tures just described were visible; but though the systematically undertaken, will assist in the solution
region occupied by and p was somewhat darker of the vexed problem as to the present existence of
than the surrounding floor, no trace of the borders lunar activity. The dusky areas of Dr. Klein are
of p, so distinct under a high sun, could be distin- all situated in disturbed regions where, if any-
Thos. Gwyn Elger.
guished. At or near full moon the borders of p are where, we should look for volcanic manifestations.
always well defined; but the only trace of areas
Kempston, Beds, 12th March.
that can then be made out are faint indications of
the ridge h, k, and a band of shade somewhat
lighter than the tone of p, bordering the wall of
Alphonsus. At this stage of illumination, only the
more westerly of the two objects on the area, p, is
visible as a delicate light spot.

ponents? I have compared 126 Tauri with 32 Orionis. The form of the discs looked different at once, the elongation of 32 Orionis being towards 180°. On December 23 and 29 I had two observations of the 4 mag. K Pegasi, called by Webb "one of Bu's closest pairs-perhaps 0-2." My

first observation has this note: "very close indeed
more difficult than 126 Tauri"; but no angle of

position is given. On the 25th I have this note:
" Pegasi, 65° to 70°; Equulei much easier." On
January 11 I observed 20 Persei. Webb says, "Bu
6.5 extremely close pair, 0-25"" but no angle of
position given. My note runs, "20 Persei, elong-
ated 310° to 330, air frosty, disc unsteady. Dist.
On x Andromeda I have two
comes well seen.'
observations. January 20, 1884, 5h. 30m., all but
divided; air unsteady. January 22, before dark
x Andromeda, depression between' discs. Discs
exceedingly small. At times just in contact and
perhaps split. On 7 Tauri I have, January 30,
1884, air good, very pretty, neat and split. I hope
"H. S." will correct me where I am wrong in these
delicate observations. Will he also give me the
exact position of 126 Tauri? According to my
circles I find 5h. 31m. + 16° 26'. It has a small
star n.p. a good way off.

C. M. Gaudibert.
THE CHADDERTON LIMELIGHT

126 TAURI, ASTRONOMICAL GASI, 20 PERSEI, ANDROMEDÆ, 7 TAURI, 32 ORIONIS. [22482.]-IN letter 22120, No. 977, page 321, H. S." kindly directed The satisfactory observation of the minute detail of these interesting features requires, of course, large of the ENGLISH MECHANIC, apertures and unusually good observing weather; my attention to and Geminorum, and to 126 but possessors of "common telescopes need not be Tauri. The two first-named stars I have reserved deterred from devoting themselves to the work of for a later time, until I have silvered anew my recording and drawing what they see. The posi- mirror. As for 126 Tauri, I have obtained eight tion and form of the dark areas should be carefully observations, never but once having good air. noted from time to time under various angles of However, all my observations point to an elongaillumination, as, if Dr. Klein's conjecture that they tion in the same direction, the mean of which is are visible manifestations of volcanic forces still in 258. Will H. Say, if I am near the truth, active operation be true, we may reasonably hope and what is the actual distance between the com