CHEAP FIXTURES FOR THE HATCHING OF SALMON. 959 



choose common wire-cloth, 12 wires to the inch or finer. The article 

 sold at all the hardware shops for window screens is very suitable ; being 

 already painted thoroughly it requires but a single coat of asphaltum 

 varnish to fit it for use. 



All iron wire must be protected from rust by painting or varnishing in 

 a most thorough manner. The commonly used material for this purpose 

 is asphaltum varnish. The so-called parafiine varnish, a coal-tar product, 

 is much inferior. It is very uneven in quality, but generally dries very 

 slowly and has a penetrating and disagreeable odor. It is best to have the 

 wire-cloth cut of the proper size, rolled perfectly flat, and then varnished 

 with two or three coats on the edges that are to lie against the wooden 

 fi^me. The rest of the varnishing can be done after the wire is attached 

 to the frames. Two good coats, very carefully laid on, is the least that 

 will answer for iron not previously painted, and three coats are much to 

 be preferred. For nailing to the frames use tinned tacks. 



There is, after all, a good deal of trouble in securing a thorough spreading 

 and adhesion of the, varnish, and it is much to be hoped that some better 

 material will soon be discovered. I have tried iron wire, tinned after 

 cutting up, and for a single season it has worlied well ; but I fear the tin 

 will not be permanent enough. Brass wire, nickel-plated, is admirable 

 but expensive, — costing about 60 or 70 cents per square foot. For the 

 present, therefore, iron wire is recommended. There should always be a 

 surplus of trays, so that if any of those in use are found to rust badly they 

 can be exchanged for newly varnished ones. 



9.— ARRANGING THE TRAYS FOR WORK. 



The trays must not be placed on 

 the bottom of the trough, but on a 

 support raised a little distance above 

 the bottom. As it is very desirable 

 to have the trough as free as possible 

 from obstructions, it is best to pro- 

 vide a temporary support for the 

 trays, like that shown in Figure 8. 

 Take a long, narrow strip of wood a 

 quarter of an inch thick and drive 



Fig. 8. 



through it, at proper distances, nails one inch long. Set the points of the 

 nails a quarter of an inch into the floor of the trough and the top of the strip 

 will then be three-quarters of an inch above the floor. On two of these sup- 

 ports, placed at a distance of a quarter or half inch from the sides and run- 

 ning the whole length of the trough, rest the hatching-trays. Supports 

 , touching the sides of the trough will not answer, because they form, with 



