FLY-MAKING BY ARTIFICIAL LIGHT. 61 



due to an author to whom Anglers are indebted for much useful and 

 trustworthy information. 



" In the earliest attempts I used a gas lamp, but this was soon discarded in 

 favour of a paraffin lamp, and this in turn gave way to a colza lamp, as giving a 

 much softer light and far less heat. With either of these illuminants I used an 

 ordinary engraver's bottle or globe, to direct the light on to the fly in the jaws of 

 the vice. The engraver's globe was filled with a solution of sulphate of copper, 

 with a small quantity of liquid ammonia, and the blue fluid, acting as an absorbent 

 of some of the coloured rays, tempered the light so as to render it less trying than 

 when taken through a colourless medium. Since then, as the outcome of numerous 

 microscopial experiments directed to producing at moderate cost and without 

 complicated apparatus, a light which is practically monochromatic, it was dis- 

 covered that this result could be obtained by filtering the light of an ordinary 

 lamp through a solution consisting of 160 grammes pure dry nitrate of copper, 14 

 grammes of chromic acid, and water added to make up to 250 c.c. This liquid is 

 held in a flat bottle, of which the parallel sides are half-inch apart. This solution, 

 reduced by the addition of water in proportion to the increased thickness of the 

 medium in the engraver's globe, will be found preferable to the old solution of 

 sulphate of copper and liquid ammonia. With this form of apparatus the illumi- 

 nation with diffused light directed on to the object was fairly well attained, and 

 there was nothing in the way of the fingers. The system, however, had the grave 

 fault of subjecting the eyes to too much glare. After trying various forms of 

 shades worn over the eyes, all of which were more or less uncomfortable 

 and inconvenient, I eventually made a large opaque brown pasteboard screen, 

 with a round hole through it to admit only sufficient light to illuminate the 

 object. This arrangement was moderately successful, but it had the great dis- 

 advantage of leaving the greater part of the working table in darkness, so that it 

 was not easy to find the wax, feathers, scissors, pliers, itc., when required for use, 

 and after a time the idea of dressing flies at night was temporarily abandoned. 



" Later, however, when removing to another house, I fitted up a room in 

 accordance with my own design, providing amongst other things, a convenient 

 working-table, fixed in a bay window, facing nearly due west, so that, as far as 

 daylight was concerned, there was practically all that could be desired. Having 

 adopted electric lighting throughout the house, I had the wires carried to an 

 ordinary concentric wall plug just above the level of the table, and resolved at 

 leisure to try and work out the problem under these conditions. 



"After exhaustive consultations on the subject, a good friend, an engineer by 

 profession, with a first-rate knowledge of optics, designed a lamp, which having 

 successfully stood the test of nearly a year's use, may, I think, be deemed fairly 

 perfect for the purpose. It is entirely of bronze and consists of a heavy foot, on 

 which is raised a hexagonal pillar, 18 inches in height. The fitting to hold the 



