13% THE MICROSCOPE. 



AT the meeting of the American association for the advancement 

 of science, held at Montreal, Dr. B. W. Carpenter, the emi- 

 nent microscopist of London, gave an address. We quote a few of 

 his statements. "Increased angle has given great power of resolu- 

 tion, but what else? Nothing at all. Angle can only be obtained 

 by lessening the working distance. The result is we see nothing 

 but what is in the focal plane. * * * The best lenses have as 

 large an angle as is compatible with requisite focal depth. * * * 

 It has been claimed that low powers of high angle are equal to 

 higher powers; that a ^ with wide angle will do everything. It 

 will resolve tests, but its continued use will injure the eyes. * * * 

 Dr. Dallinger believes if he had worked with a ^ instead of a ^ he 

 would have injured his eyes. I hear of Americans making one-inch 

 objectives up to great angles, for which the society screw is too 

 small. This makes a very bad ^ and spoils it for a one-inch. * * 

 High power eye-pieces are valuable for testing objectives. * * * 

 The flagellae of Monas termo would probably not have been found 

 without the wide angle lens, but now that they are known to exist, 

 they have been seen better with a lower angle. A ^ inch of 40' was 

 ordered of Powell & Lealand, who at first were unwilling to make 

 such a low angled glass, but finally did so, and at a public soiree it 

 was exhibited by the side of a ^ inch of 90", and the diiiference be- 

 tween them was so striking as to attract universal attention and 

 commendation of the low-angle lens." 



THE exhibits at the American Society were very fine. The ex- 

 hibit of 



JAMES W. QUEEN 



was under the charge of Mr. Edward Pennock. Eight compound 

 microscopes were exhibited, together with an interesting variety of 

 microscopic objects, books, accessories, etc. A low-power objective 

 was much admired. The power of this objective is increased or 

 decreased by the turning of a graduated collar. The field of this 

 objective ranges from five-eighths to two inches across. Com- 

 plete sets of Professor Abbes' diffraction plates and diaphragms were 

 exhibited. A new mechanical finger, designed by Prof. Kain, was 



