538 Sir David Salomons [Feb. 26, 



measure 4J inches apart under this magnification) ; a wave length 

 40Q00 inch, therefore, on screen measures about ^ inch. 



The Polariscope. — Shown with parallel light ; plain glass ; glass 

 under j)ressure ; chilled glass (round, oval, and waved peripheries) ; 

 Prince Eupert's drof) (broken in the field) ; horn ; selenites (over- 

 lapped) ; butterfly (selenite) ; bunch of grapes (selenite) ; bi-quartz, 

 with i-wave plate (the :^-wave plate in this experiment produces the 

 same effect upon the bi-quartz as if a column, 20 centimetres long, of 

 a 7^ per cent, solution of cane sugar were placed between the 

 polarising nicol and the bi-quartz. The analyser has to be rotated 

 about 10^); a piece of sapphire to show asterism. Shown with con- 

 vergent light ; hemitrope (cut in a j^lane, not at right angles to the 

 axis) ; ruby ; topaz ; grape sugar (diabetic) ; cane sugar ; quartz ; 

 superposed right and left-handed quartz (spirals) ; calcite and phena- 

 kite superposed (showing transition from negative to positive crystal, 

 passing through the apopholite stage). 



TJie Solidiscope. — New form of apparatus for showing solids, and 

 consisting of two reflecting prisms and suitable projecting lenses. 

 With this instrument were shown : — Barton's button, the works of a 

 watch, a coin. 



Spectrum Analysis. — Spectrum thrown by means of a disulphide 

 prism, combined with a reflecting prism ; the result being that a 

 good spectrum is thrown upon the screen direct without turning the 

 lantern. There were shown : — The spectrum ; absorption bands 

 of chlorophyll, &c. ; effects produced by passing the light through 

 coloured gelatine films. 



Projection of Slides. — Decomposition of water ; expansion of a 

 wire by means of heat ; combination of colours to form white light ; 

 various diagrams, coloured photographs of a workshop, &c. As an 

 extra experiment there was shown, in the polariscope, with a con- 

 vergent light, Mitscherlisch's experiment (illustrating the changes 

 which take place in a selenite under the influence of heat). 



There are but few who would disagree with me in the opinion 

 that the microscopic world, as regards its design and its molecular 

 structure, is quite as wonderful as the great works around us seen 

 with the unaided eye. A magnifying glass of low power opens up a 

 world far larger than that w^hich we are accustomed to see. At the 

 present time, even with the most perfect apparatus that exist, only a 

 small portion of the universe is known to us. 



Scientific study should be pursued by all in a greater or less 

 degree. It teaches more important lessons than the most impressive 

 discourse ever preached. During the investigation of what is 

 generally termed the invisible world, men should at times pause to 

 reflect, and ask themselves such questions as these : What is the 

 meaning of, and to what end is, creation ? Is it all mere chance ? 

 Were such wonderful designs and properties created at the beginning ? 

 Was there in matter at the beginning an inherent, or implanted, 



