16 



FKESH-WATER AQUAEIA. 



wkich is to be cut, and nail them to the bench — they should be 

 just wide enough apart to admit a tenon-saw — and with the 

 saw out the line to the required depth, ^in. Without some 

 such preparation as this it would be difficult to cut the sides of 

 the grooves with the necessary accuracy. When both lines 

 have been sawn in this way, take a chisel and maUet and cut 

 out the slate which lies between them. But before using the 

 chisel take the precaution to put two or three folds of carpet, 

 or the like, between the slate and the bench to prevent all jarring 

 and the danger of a crack. These grooves are to receive the 

 ends of the bottom- 

 There is another way of making the outs for these grooves. 

 It is this: Get a piece of hoop-iron, 

 about a foot long, and straighten 

 it. Then for a handle procure lOin. 

 of broomstick, more or less, saw it 

 half through lengthwise, and hammer 

 the hoop-iron into the groove. Mark 

 with an awl the place on the slate 

 where the cut is to be made — and 

 deepen this mark a little by running 

 the point of a three-cornered file a 

 few times carefully up and down. 

 Fill the slight groove thus made 

 with fine white sand, and moisten it 

 with water by means of a wet brush. 

 Now rvm to and fro in this sand and water the edge of the 

 tool which has just been made. By continually doing this, 

 always keeping plenty of sand and water under the edge of 

 the iron, the cut will gradually become deep enough. When 

 the cuts have been made, the portion of slate between them may 

 be chiselled out as before directed. As a rule, the slate can be 

 split cleanly out by striking the chisel against the edge and not 

 on the top of the slate, and there is less danger of breakage. 

 The latter method of making the cuts is the more satisfactory 

 of the two — the former so quickly blunts the saw. 



Now along both sides of the bottom and of each end, cut, at 

 a distance of Jin. from the edge, grooves ^in. deep and fin. 



Fig. 25. End of Slate 

 AftUARiuM (Fig. 8), show- 

 ing Grooves for Glass 

 Sides and Slate Bottom, 

 and Holes for Bolts. 



