EQUIPMENT, APPARATUS, AND LIBRARY 13 



Glass. Double-thick window glass for sides and ends, and ribbed 

 skylight glass for bottom for sizes above 20 x 10 x 12 inches. 

 For smaller sizes, waste 10 x 12 in. negatives are good and 

 cost little or nothing. 



Angle or valley tin, sizes indicated below. 



Aquarium cement. 



Solder. 



Green or black carriage paint and a little spar varnish. 



FIG. 6. Making aquaria 



From left to right, laying the cement ; glass set in one, with bent green twigs 



to hold it in place ; painting frames, and frames of different sizes, 5x7x4 to 



24x15x10; cutting the angle tin to measure; soldering the frame held in a 



square fastened to table 



Tools. Every laboratory should be provided with a few simple tools, 

 among which the following will be required in making aquaria : 



Carpenter's square, to hold the frame perfectly square at each 

 angle while it is being soldered. A three-way square, made by nailing 

 two 5-inch boards of convenient length at exact right angles and fasten- 

 ing them to a work table, greatly facilitates getting each angle right at 

 the first trial. 



