804 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



necessary to have recourse to a compound Microscope. I have endeavoured 

 to modify the form and mode of illumination of this instrument whilst 

 preserving a sufficient power to make it applicable to all cases. The 

 arrangement which I have devised having appeared to some of my colleagues 

 to be very practical I will give here a short description of it. 



The instrument consists of an ordinary Microscope tube, sliding smoothly 

 in another tube, which is closed at its lower or objective end by a kind of 

 screw cover which has a small aperture in the centre, which acts as a 

 diaphragm. At the plane of this diaphragm the tube has a slit for the 

 introduction of a slide. A ring sliding on the tube presses on the slide 

 and fulfils the same functions as the clips of a Microscope. The object is 

 illuminated by directing the instrument like an opera-glass to a white cloud 

 or any other brightly illuminated object. The light from these large natural 

 reflectors is sufficient for a power of 250 diameters, a power which it is 

 useless to exceed for the purpose in view, and which it will be very rarely 

 necessary to reach. The preparation of the object to be examined is effected 

 in the field in a very simple manner, the cover-glass adhering sufficiently 

 to the slide to allow of all possible positions being given to the 

 instrument. The diaphragm can be readily removed when it is necessary 

 to alter the tube. 



As will be seen, I have been obliged to give to this Microscope as simple 



an arrangement as possible in con- 

 FiG. 211. sequence of the accidents to which an 



instrument of this kind is exposed 

 during botanizing. I hope that, not- 

 withstanding its little complication, 

 it will be useful to botanists who are 

 addicted to the investigation of the 

 lower plants, or even in a more 

 general way, to naturalists who have 

 taken as the object of their studies 

 the microscopical organisms." 



Rochester Magic Lantern and 

 Projection Microscope. — Without 

 committing ourselves to the state- 

 ment of the designers (the Bausch and 

 Lomb Optical Co.) that this, fig. 211, 

 is " the neatest, cheapest, and best 

 lantern ever introduced," and " with- 

 out exception far superior to any 

 other both for its size and price," 

 it may be admitted that it is a very 

 handy little lantern (8 in. high). It 

 is made entirely of brass, lacquered, 

 and is so arranged that ordinary 

 3 X 1 in. slides can be used, and 

 the image projected on a screen. 

 An additional recommendation (to utilitarian Microscopists at any rate) 

 is that the lamp " being a regular hand-lamp, makes the lantern more 

 valuable, as the same can be used at any time about the house." 



Schott's Microscopes.— On pp. 148-150 we directed attention to 

 certain figures of Microscopes from Schott's ' Magia Universalis,' published 

 in 1657, which had long puzzled microscopists by their apparently excep- 

 tional and extraordinary size. We submitted an explanation, namely, that 



