1872.] Light. 529 
Prof. Morton writes to say that, from information received from Dr. Schel- 
len, it would appear that M. Duboseq had previously been the maker of an 
apparatus for projecting horizontal objects, which involved all the essential 
features of the vertical lantern described by Prof. Morton in an earlier number 
of this Journal (p. 396, July, 1872), the apparatus constructed by M. Duboscq 
being, however, entirely unknown to Prof. Morton. 
Microscopy.—A new instrument for making microscopical drawings is 
described by Mr. Isaac Roberts, F.G.S., in the ‘‘ Monthly Microscopical 
Journal,’’ vol. viii., p. 2. It consists of an adaptation of the pantograph used 
in copying drawings. The smaller ends of the levers carry a thin glass disc, 
with two cross lines ruled upon it: this is inserted in the eye-piece through a 
slit in its side, and acts as a pointer; the pencil is attached to the opposite 
extremity of the levers. When in use, the paper is supported on a desk level 
with the slit of the eye-piece. The pencil is guided with the right hand, the 
centre of the cross lines being moved over the objeé& to be delineated while 
looking through the microscope. This contrivance, although very ingenious, 
has most probably the defects of the ordinary pantograph, which can only be 
used with advantage for the reduction of drawings, its powers of execution 
being defective when used to enlarge, or even to copy, on the same scale. 
Mr. Walter White, in ‘‘ Science Gossip” for August, describes an ingenious 
machine for cutting vegetable sections. The great novelty is the use of a 
wedge for raising the substance to be cut, instead of the usual screw with 
micrometer head. The author claims for his invention the advantages of 
cheap construction and efficiency. As a cutting instrument, Mr. White re- 
commends a good ordinary razor, fixed in a bradawl handle and carefully 
sharpened. For cutting transverse sections, the stems—previously prepared 
by soaking-~are fixed in a cork just fitting the tube of the section-instrument ; 
herbaceous stems are best packed in strips of the same stem. Leaves should 
be placed between the two halves of a cork, cut lengthwise. Seeds, and other 
small objects, are best cut when bedded in a mixture of wax and spermaceti, 
formed into a plug by casting in the tube of the section-instrument. Wood 
for cutting longitudinal sections can be fixed in the same manner. The razor, 
while cutting, should be kept constantly wetted with methylated spirit, in which 
stems for cutting are most conveniently preserved until wanted for sections. 
Dr. R. H. Ward, in a paper read before the Medical Society of New York, 
gives a valuable analytical catalogue of the objectives and medical and stu- 
dents’ microscopes procurable in England, on the Continent, and in America. 
The table of objectives comprises those of twenty-seven makers, giving the 
nominal focal length, angular aperture, and price, with numerous explanatory 
remarks. This is followed by a synopsis of students’ microscopes, in which 
the advantages and disadvantages of the several patterns of stand, the mate- 
rial used in construction, and the various appendages of the instrument, are 
all clearly stated. A list of accessory apparatus is given, distinguishing 
between that absolutely needed and that which may for some special purpose 
be desirable. The paper concludes with a list of nineteen students’ micro- 
scopes of American construction, giving name of maker, model of stand, 
height in inches, weight, diameter of tube, material, adjustments furnished, 
details of stage, mirror, oculars, objectives, range of magnifying power, acces- 
sory apparatus, and price in dollars. It would have been well had this care- 
fully classified table included the instruments of English and Continental 
opticians, as inthe author’s list of objectives. The paper is, however, valuable 
as giving in a convenient form the substance of the catalogues of a large 
number of microscope makers. The paper is reprinted in the ‘‘ Monthly 
Microscopical Journal’? for August. 
M. Mouchet, in advocating the use of coloured glasses in Microscopy, for 
the purpose of saving the eye-sight, reviews carefully the various positions in 
which they may be placed: these are four in number,—before the mirror, 
under the objea&, between the objective and eye-piece, and, lastly, above the 
eye-piece itself. The position before the mirror necessitates the employment 
of glasses of acertain size, but gives good results, and, when the coloured 
VOL. I. (N.S.) Say 
