xvi Proceedings. [March gth, 1915. 



Thomas Thorp. It is made by producing a special type of matt 

 surface on glass, on which is then deposited silver. This forms the 

 opaque back of the screen, the front being of transparent glass. 

 The screen gives a well-illuminated picture when employed for 

 ordinary lantern work and is especially good for use with the 

 projecting microscope. By its means the Brownian motion of 

 colloidal particles, which requires high magnification and great 

 loss of light, can be demonstrated whereas other types of screens 

 were found to be of little use for this purpose. The screen is 

 most effective when viewed at an angle nearly perpendicular to its 

 surface. The surface brightness falls off as the angle from the 

 normal is increased and at about 33 is only equal to that of 

 white blotting paper. A microscopic examination of the sur- 

 face shows that it is made up of minute convex discs. 



Mr. Harvey Thorp described some of his father's experi- 

 ments made with the view of producing improved screens for use 

 with the Kinematograph, and Mr. Arthur Adamson explained 

 the result of measurements which helped to explain the special 

 optical properties of the screen. 



Professor G. Elliot Smith, M.A., M.D., F.R.S., read a 

 paper entitled "The Significance of the Geographical 

 Distribution of the Practice of Mummification." 



This paper will be printed in full in the Afemoirs. 



General Meeting, March 9th. 19 15. 



The President, Mr. Francis Nicholson, KZ.S., 

 in the Chair. 



Mr. Hknry Ward Kearns, B.Sc, J. P., of " Boothroyd" 

 Brook/ands, near Manchester, was elected an ordinary member 

 of the Society. 



