44 



THE AMERICAN MONTHLY 



[Feb. 



all round, which is advisable, though not esssential. lu 

 this slate, at a distance of about an inch from the edge 

 all round, you have to make grooves with holes at the ends 

 for the bottoms of the pillars, see Fig. 1. These holes 

 should be about 1 in, in depth and the same in breadth; 

 the grooves should be about i in. broad and at least 1 in, 

 deep. You now have to construct the pillars, which are 

 made of hard birch wood — or maliogany will do- — and 

 are shaped as Fig. 2, The sides are, in my opinion, best 

 square, but you can make them round if you prefer it. 

 If square, the sides may measure 2 in. in breadth ; if 

 round, they ought to be at least 2i in. in diameter. The 



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ends are, of course, to be cut to a circle about 1 in. in 

 diameter, or, better, shaped to accurately tit the holes 

 made in the slate bottom. The part thus shaped will, 

 therefore, be about 1 in. long, while the middle (square) 

 part will be about 14 in. long. Down the middle of the 

 pillars, on two sides, at right angles, are to be cut grooves 

 about \ in. broad and at least ;i in. in depth. Some may 

 think my measurements unnecessarily large, but I have 

 sutfered so severely in bygone years from aquaria which 

 leaked that I am quite resolved that if my measurements 



