ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 477 



M. Durnaige has devised an instrument which while packing into a 

 small compass, has all the conditions of perfect stability and all the 

 improvements which are applied to large laboratory Microscopes. 



When set up the instrument is an inclining Microscope of ordinary 

 dimensions. It can be divided into two parts ; the first comprising the 

 stem and the tube ; the second the stage and the foot. 



The standard is fixed on the stage by a screw of special construction 

 having four threads. This mode of construction assuring very great 

 stability, it has been possible to make the standard very short. Owing 

 to the arrangement of the screw it is sufficient to turn the standard 

 half round to fix it in the stage perfectly securely. 



The lower part of the Microscope can be reduced to minimum 

 dimensions by [rotating the stage and short pillar 180° and then in- 

 verting the stage on the hinge by which it is connected with the pillar] 

 and placing it between the feet of the base. 



Thus divided and folded the Microscope occupies only a small space, 

 and can be placed in a case of reduced dimensions " (6 in. x 6 in.). 



A special condenser is added, differing, however, from the Abbe form 

 only in its mechanical part, which is arranged so as to take up only a 

 very small space. 



Nelson's Mechanical Stage. — In bringing before the March meeting 

 a new mechanical stage, Mr. E. M. Nelson said he "desired to point out 

 that, in designing a Microscope, one had to guard against falling into 

 one of two errors — over-complexity on the one hand, and over-simplicity 

 on the other. It must be remembered that over-simplicity is an error 

 just as great as over-complexity ; it is to be feared that in consequence 

 of so much notice having been given to over-complexity (and surely it 

 was wanted), the other error of over-simplicity has been neglected. It 

 is almost an abuse of terms to call the heavy-footed, non-inclining, 

 Continental abomination, with its spring-clip stage, small aperture, and 

 with a sliding-tube coarse-adjustment, by the now exalted name of 

 Microscope. As to stages, it would be hard to invent a worse form 

 than that usually found in Continental stands, consisting of a small flat 

 stage, one small hole, and spring clips." 



Mr. Nelson then described his new stage as follows : — 



" The stage, which is of my horseshoe form, has two narrow vertical 

 slots cut in it, one on either side of the opening. The usual rack-and- 

 pinion which is placed underneath the stage, moves blocks sliding in the 

 vertical slots. These blocks come flush with the stage, and have a screw 

 in them, the head of which, projecting above the stage and pressing 

 against the lower edge of the slide, pushes it up. The position of the 

 Microscope is assumed to be an inclined one, then on turning back the 

 pinion the slide drops. In fine, the slide is kept against the screw-heads 

 by gravity, the Microscope being inclined. 



As the blocks only come up through the slots flush with the stage, 

 the screw-heads alone projecting, a plain stage may be obtained at any 

 time by removing the screws. Or, if preferred, a bar may be fixed by 

 the screws to the blocks, which will make a mechanical sliding bar. 



This last is the form I have adopted in my own Microscope. In 

 addition to the vertical, a horizontal movement may be fitted in the same 

 way by slotting the stage and moving a block by a screw underneath. 

 Such a fitting has been put to the Microscope before you. It is obvious 

 that by such a method one can push the slide across the stage ; but there 



