144 The Microscope. 



concentric stand; copper-and-magnesia-sulphate by polarized light, 

 taken from an incandescent lamp lighted by a Gibson storage 

 battery ; a line specimen of the head of a dragon-fly on a universal 

 stand, and a section of black marble on a model stand with a para- 

 boloid illnmination. 



The exhibit of Dr. A. J. Watts was particularly admired, being 

 prismatic gold-crystals on a Beck binocular with upper light, and 

 fern-gold on a Beck monocular. Plant hairs of Shephe)xlia canaden- 

 sis was exhibited by Mr. E. C. Chapman, on a stand entirely con- 

 structed by himself and which bore testimony to his skill. 



Mr. Geo. M. Hopkins' exhibit was a center of a throng of 

 interested spectators. The path of the electric spark on blackened 

 glass occupied one stage ; the beautiful phenomenon of Newton's 

 rings, another, while the third bore a slide of salicin-discs rotat- 

 ing in opposite directions, by means of a mica shield covering one- 

 half the lield. 



Prof. W. C. Peckham's exhibit occupied a table by itself and 

 was well worth the wait necessary to get within seeing distance of 

 his objects. On the first microscope was a specimen of the car- 

 niverous plant hairs of sun dew {Drosera filifolia) with paraboloid 

 illumination. No. 2 was occupied by a drop of Eidgewood (city) 

 water, and judging from the remarks of the uninitiated this was the 

 only disapi:»ointment of the evening, the ladies particularly ap- 

 proaching the stand with a don't-let-them-get-loose look upon their 

 fair features, and surprise was mingled with satisfaction when they 

 discovered that the tigers and hyenas which they expected to see did 

 not exist. On the professor's fourth table was a splendidly illumi- 

 nated specimen of raphides in Allium satirvum (garlic). 



Mr. H. L. Brevoort showed a fine section of Cornus florida 

 (flowering dog- wood) by polarized light. On this stand the polar- 

 ized prism was rotated by an ingeniously contrived clock-work tram. 



Mr. G. E. Ashman had a specimen of insect imprisoned in gum 

 copal (fossil) from Zanzibar, which attracted much attention. 



Bacteria termo was well shown by Dr. C. N. Hoagland under 

 a Zeiss -^-g oil immersion objective. 



Mr. G. D. Hiscock displayed a finely- arranged slide of diatoms 

 by Prof. C. H. Kane, of Camden, N. J., and the head of a diamond- 

 beetle. 



Mr. John Green, now with Prof. A. K. Eaton, but formerly 

 with Robert Tolls, exhibited A. Pellucida with a y^ homogeneous im- 

 mersion of 1.40 N. A., and notwithstanding the constant vibration 



