1897J MICROSCOPICAL JOURNAL. 171 



"The microscope," said Dr. Nelson, "has made greater 

 revehitioiis than the telescope. The views which you shall 

 behold this evening-, projected from a polarizing- ap])aratus 

 perfected by Dr. Van Dyck, have not been shown to an 

 audience of this kind before." 



Dr. Van Dyck then explained the polarizing- projection 

 lantern, g-iving- the theory of lig-ht vibrations and telling- 

 the effects of interference between waves of lig-ht. Polar- 

 ization is ac(iuired when all ])arts of a medium move alike 

 and in the same direction. By means of a bundle of glass 

 plates, arrang-ed in a certain w^ay, he had perfected the 

 projecting- apparatus. 



While Dr. Van Dyck manag-ed the lantern, assisted by 

 Frederick H. Blodgett, secretary of the society. Dr. Ches- 

 ter explained the views. They were mag-nified from the 

 slides 160,000 times, being- projected from a one-quarter 

 inch aperture to an area upon the screen of about eig-ht 

 feet. 



"Beautiful" is too feeble a word to describe the tints 

 which the rock crystals and the org-anic particles assumed 

 under polarized lig-ht. Ag-ain and ag-ain, as the more ex- 

 quisite specimens were shown, the audience g-ave expres- 

 sion to its delig-ht in applause. When inorg-anic speci- 

 mens — crystals formed by chemicals — were projected, 

 much amusement was occasioned. By some arrang-ement 

 of the apparatus, the crystal "wheels went around," chang-- 

 ing- their hues the while. 



Part II of the scientific entertainment was held in the 

 lecture room in the rear of the chapel. Here were half a 

 hundred microscopes, with specimens well mounted and 

 displayed under both electric and oil lig-ht, arranged on 

 tables. The visitors passed up one row of microscopes, 

 peeping- into the tubes as they walked, and down the other 

 row. These were the exhibitors and their exhibits: 



Colleg-e ExperimentStation; Photo-microg-ra])hic Camera 



Dr. J. B. Smith; Eg-g-s of the Tajie-worm. Head of the 

 Tape-worm, Mouth of the House-lly, Mammalian Sperm, 

 Wing- Cover of a Beetle. 



