MahciiI, 1S6G.] 



SCIENCE-GOSSIP. 



Gc 



MICROSCOPY. 



Object Mountek. — Annexed is a sketch of a 

 contrivance which I made some years ago, in con- 

 sequence of having been very much annoyed by 

 reason of objects, not quite flat nor in a cell, purg- 

 ing, or sliding away from their central position on 

 the glass-slide, as soon as any pressure was applied 

 to the thin glass-cover. This matter is referred to 

 in Wood's " Common Objects of the Microscope," 

 p. G2, and every practical microscopist has ex- 

 perienced the difficulty of applying the requisite 

 pressure to the cover without tilting it more or less, 

 and so driving the object towards one side or the 

 other, and no contrivance described in the hand- 

 books, be they American clip, wire spring, whale- 



S 



s 



Fig. 80. 



bone, or spring steel, appears to be of any use in 

 preventing this frequent calamity. This contrivance 

 of mine, however, which was made for me by a 

 country carpenter, and cost 10c/., quite meets the 

 necessities of the case, as ensuring a pressure per- 

 fectly steady, parallel, and graduated, the three prin- 



cipal desiderata in mounting. A is a solid piece of 

 mahogany, of the size drawn ; B, a small rod (or 

 lead pencil), passing easily, but without lateral 

 shake, through a hole in A, and having its lower 

 end cut off perfectly flat and fitting the platform C 

 so truly that, on holding the mounter up to the 

 light, no interstice nor unevenness of fit may appear ; 

 D is a small hole, through which and through E an 

 indiarubber band is passed, and so over the notch 

 in the upper end of the rod or pencil B, which is 

 also sometimes made much longer than in the 

 sketch, and notched on one side as at H, so that by 

 altering the position of, or adding an additional 

 indiarubber band, any required pressure may be 

 obtained. The position of the glass slide is in- 

 dicated by the dotted outline.— TT. L. Sear. 



Spring- Clip. — Allow me to suggest an improve- 

 ment in the spring clips described by your corre- 

 spondent William Goode, iu last month's Gossip. 

 It is this — that underneath the point where the 

 centre of the glass slide would come, a hole should 

 be drilled with a centre-bit ; five-eighths of an inch 

 in diameter would be a useful size. The advantage 

 of this would be, that the slide could be examined 

 whilst under pressure, and the presence of air 

 bubbles, or the shifting of an object, detected 

 before the balsam had set. If these holes were 

 made to taper slightly from below upwards, bght 

 could be more easily admitted to the under surface 

 of the slide. — E. M. 



Pipette. — The figure represents 

 a very convenient form of pipette 

 for washing minute objects after 

 immersion in caustic potass ; it 

 consists of a bulbous pipette tube, 

 one end of which is drawn out in 

 a gas flame and bent nearly at 

 right angles, and having a very 

 small aperture left therein, the 

 other end being slightly trumpeted 

 for convenience of holding it in 

 the lips ; if, now, the bulb be 

 partly filled with water, a fine 

 stream of greater or less force, as 

 may be required, can be propelled 

 by the breath of the operator 

 upon any portion of an object 

 as it is held in a forceps or on a 

 slide ; and, what is of greater im- 

 portance, it leaves both his hands 

 at liberty for any necessary ma- 

 nipulative process during the 

 operation. — W. L. Sear. ■ 

 Illuminators. — Will you allow me to point out 

 an error in the description of " New Illuminators 

 for High Powers " in your last number. It is said 

 that the "principle of reflection employed in the 

 transit instrument has been modified and brought to 

 bear upon the microscope." If it is merely meant 



f^ 



< 



Fig. 81. 



