46 THE AMERICAN MONTHLY [Feb. 



two or three coats of varnish, made by dissolving sealing- 

 wax in methylated spirits of wine. When the pillars are 

 fixed in their places, you can proceed to insert the glass. 

 This is what is commonly called "32in." sheet glass, and 

 is cut to exactly fit the grooves. The panes are firmly 

 bedded in with the cement, and a light frame work is fit- 

 ted on the top to hold all together. This framework is 

 shown in Fig. 3. It is merely a frame about 1^ in, in 

 width and one-half inch in thickness. The top of each 

 pillar, above the square part, is cut to this length and in- 

 serted in the holes at the corner, and small knobs are in- 

 serted at the corners to give the tank an ornamental ap- 

 pearance. If a glass top is wished for, the frame is cut 

 with a rabbet about J in. wide all round on its upper 

 surface to receive the edges of the glass. The final ap- 

 pearance of the tank is shown in Fig. 4. 



If the tank has to stand in a very sunny situation, I 

 think it is decidedly advisable to provide some means or 

 other of keeping out the superfluous light, as it acts 

 most injuriously on the creature in it; and causes such a 

 growth of confervsB on the sides that it is a continual nui- 

 sance to keep them clean. For this purpose I have al- 

 ways considered it best to have light- shutters of thin 

 wood constructed which will just go inside the frame 

 formed by the bottom, top frame, and pillars, and outside 

 the glass. This is done so easily that it requires no fur- 

 ther description. I think this plan is desirable, because 

 it allows of the complete closing of the sides of the tank 

 in summer, when the weather is warm, and allows the 

 shutters to be removed when it is desired to see any ob- 

 ject close to the glass, or when the weather is cold during 

 the winter. It is, therefore, much to be preferred to 

 making the sides or ends permanently of slate. 



In this series there is not space to describe further de- 

 velopments of the construction of the tank. It is also 

 unnecessary, for any one, given the above details, can 



