1897J MICROSCOPICAL JOURNAL. 171 



"The microscope," said Dr. Nelson, "has made g-reater 

 revelations than the telescope. The views which you shall 

 behold this evening-, projected from a polarizing- apparatus 

 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, giving- the theory of light vibrations and telling- 

 the effects of interference between waves of light. Polar- 

 ization is acquired when all parts of a medium move alike 

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

 plates, arranged in a certain way, he had perfected the 

 projecting- apparatus. 



While Dr. Van Dyck managed the lantern, assisted by 

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

 ter explained the views. They were magnified from the 

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

 inch aperture to an area upon the screen of about eight 

 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 again, as the more ex- 

 quisite specimens were shown, the audience gave 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: 



College ExperimentStation; Photo-microg-raphic Camera 



Dr. J. B, Smith; Egg-s of the Tape-worm, Head of the 

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

 Wing Cover of a Beetle. 



