Sept. 1, 1865.] 



SCIENCE-GOSSIP. 



SOL 



not be despised by the readers of Science Gossip, 

 however learned ; and if it may chance to meet the 

 eye of one immersed in the speculations of gain, or 

 given np to studies he may fancy more noble and 

 exalted, and who may be disposed to treat with 

 indifference subjects seeming so lowly and common, 

 let his rising contempt be checked by the reflection, 

 that the humblest thing in nature becomes an 

 exalted subject of human study, when considered 

 as an object for which Infinite Wisdom has exercised 

 design, and upon which the finger of Omnipotence 

 has put forth its power, 

 Armagh. Lewis G. Mills, LL.B. 



A NEW BINOCULAR DISSECTING 

 MICROSCOPE. 



IN making dissections of the lower animals, I 

 have frequently found that much more satis- 

 factory results are attained by the employment of 

 low magnifying powers of considerable penetration, 

 than by the use of the ineh and half-inch lenses of 

 such instruments as the Quekett microscope. The 

 advantages of low powers are : — 1st. That an 

 abundance of room is left between the lens and the 

 object, so as to admit of freedom of action of the 

 operator's hands ; 2nd. That the object may be 

 easily and well illuminated by means of the " con- 

 denser;" and 3rd. That several structures situate 

 at different levels are brought simultaneously into 

 view. Erom a knowledge of the qualities I have 

 alluded to, I was led to think that an arrangement 

 of simple lenses for the production of bhiocular 

 vision would be of infinite service to the anatomist. 

 I therefore caused such a combination to be effected, 

 and, having added to it a few contrivances calculated 

 to facilitate dissection, I now submit the result to 

 working microscopists. 



The microscope when closed and packed, with its 

 various apparatus, forms an oblong mahogany box 

 about six inches long and three and a half inches 

 deep, provided with a lock and key. When unlockedj 



the cover and one side, which are connected by 

 hinges, unfold so as to lie out in front of the 

 operator, displaying, at the same time, the lenses, 

 mirror, and dissecting instruments. The stage con- 

 sists of a gutta percha trough, having a small circle 

 of glass cemented into its centre, and placed (when 

 in use) upon ledges attached to the two ends of the 

 case. The objects of this species of stage are :— 

 {a) to enable moUusks and similar creatures to be 

 dissected under water; {b) to allow the object to be 

 fixed by means of pins which may be driven into 

 the gutta percha ; and (c) to permit light, when 

 requu'ed, to travel through a tissue, by being reflected 

 from the mirror to the glass circle. Outside the 

 real ends of the case, which sustain the trough, 

 there are two false ones, slightly bevelled above and 

 connected below with horizontal pieces, which slide 

 easily and uniformly into the bottom of the case. 

 These are intended as supports for the wrists of the 

 anatomist, and can be drawn out for a distance of 

 six inches or less on either side. The lenses, which 

 are two in number, are fixed in movable eye-pieces, 

 and these are sunk in an oblique arm, which has the 

 power of vertical rotation on the perpendicular bar 

 employed in producing the proper focus. This 

 vertical bar slides freely and steadily in a brass 

 fitting which perforates the back of the case. By 

 means of the rotating power to which I have 

 referred, the arm bearing the lenses is, when not 

 intended for use, depressed so as to fit into the 

 centre of the case. The trough also slides beneath 

 the mirror. When the object examined is opaque, 

 a " bright spot " of light is thrown upon it by the 

 condenser which springs from the front angle of the 

 case. The dissecting instruments are placed in 

 depressions in those portions of the case which 

 unfold upon the table ; they consist of two pair of 

 scissors ("curved" and "straight"), two curved 

 and two straight needles, and a pair of scalpels of 

 forms adapted to the requirements of the dissector. 

 The magnifying power, with the binocular arrange- 

 ment, does not exceed six diameters, but the field of 

 view is so large, and the "relief" of the object 

 under examination so well and clearly marked, that 

 it is not without some degree of confidence that I 

 ask the readers of Science Gossip to pronounce 

 their opinion upon the qualities of the new 

 binocular. 



Henky Lawson, M.D. 



SIMPLE OBJECTS.-VI. 



{Cosmarmm hotrytis.) 



THE pretty green frustules of Cosmarmm hotrytis 

 may be found in almost every pond, and form 

 very interesting objects for the microscope. Each 

 frustule is a perfect plant ; and consists of a single 

 cell, having a deep constriction across the middle, 

 and regularly covered with minute tubercles. The 



