365 



apparatus was exhibited as described, the Secretary asking 

 members to be as careful as possible in handling it. 



Mr. Orfeur said that some months ago he exhibited a stage 

 for producing similar effects and had since been experimenting 

 upon the advantages of various colours for the discs, and had 

 devised some, which when put into the stops gave the best pos- 

 sible results for all purposes. He found that red for the object 

 and blue for the ground — blue and dark amber — and pale saffron 

 on dark green — practically gave all the varieties wanted, 

 whilst the mode of introducing them into the field without any 

 alteration of the adjustments was a great advantage. He did 

 not think there could be anything more simple, durable, or 

 effective. 



Mr. Nelson inquired where the coloured gelatine could be 

 obtained ? 



Mr. Orfeur said he got it from Mr. Green at Dalston. It was 

 sold in packets at Is. 6d. 



Mr. Karop thought it would be a convenience if some member 

 would obtain some for distribution to others in smaller quanti- 

 ties ; no one would, of course, want to use so much as was con- 

 tained in a packet. 



Mr. Mainland said he had tried Mr. Rheinberg's plan, 

 and found that with a low power objective the effects 

 were very fine, especially with a malachite green ground, 

 but he found he got the finest effects by using plain light on 

 the object. 



Mr. Nelson said there was no doubt that very important 

 effects could be obtained by the use of these gelatine colours if 

 only the right ones were employed. Monochromatic screens 

 were of great use in almost all departments, and those hitherto 

 made were of two kinds. One of these was Mr. Gilford's plan 

 by a coloured fluid in a glass cell. The other form was made 

 by mixing up the colour in some compound and smearing it on 

 the green glass. This was not so good as the other, because it 

 was apt to be cloudy, but if they could get suitable colours in 

 gelatine such as they had with crackers they would be able to 

 make a cheap and efficient screen. 



A Member observed that the gelatine of crackers was not deep 

 enough in colour, so that it was necessary to use it in several 



