106 



GOLDFISH VARIETIES AND 



advantage that the aquarium does not have to be raised to heat from 

 underneath. The first filling of the system is not always easy. Water is 

 poured in the funnel until it will take no more. Then the hand is placed 

 over the funnel and the pipe turned upside down. Turn upright again and 

 put in more water. Hold at different angles. When it will take no more 

 water, try heat under the coil. If the water in funnel moves up and down 

 there is still air in the tube. Sometimes it can be removed by actively fill- 

 ing and discharging a fountain pen filler in the opening. When it works 

 smoothly and the heat travels past the funnel, it is all right to use. The 

 funnel must always contain water, or boiling will soon occur. Ha filled 

 bottle with small neck is inverted, stood in funnel and secured in some 

 manner, it will last a long time without refilling. The copper tubing 

 should be heavily nickled after bending into shape, as copper is fatal in 

 the aquarium. 



Fig. 75 shows a modification of the same idea with the pipe carried 

 through aquarium base. The little hook at top of the hot water system 

 was devised by the writer to avoid the necessity of filling the funnel, and 

 to have the heater more concealed. The tubes within the water are of 

 glass, connected by rubber, the end hook also being a separate piece. By 

 removing this the system is easily filled. When it is on, the vapor collects 

 in top of hook, and when enough has collected to force a bubble out, a drop 

 of water is automatically sucked back to take its place. The air space in 

 hook also prevents any circulation between hot water system and aquarium 

 water proper. This system also gives a higher percentage of heating 

 efficiency than the outside hook-on form. 



^^I^^^ 



Figs. 76 and 11. Direct Heating Through Pan and Through Metal Disc 



For the highest efficiency and greatest all-round satisfaction, note 

 should be taken of Fig. No. 76. This is a 4-inch agate pan set in the 

 cement base described on page 216. When making the aquarium it is no 

 extra labor to set this in. For aquaria already constructed it is somewhat 

 of an undertaking to cut a sufficiently large hole, but it can be done and 

 the pan cemented on top. Fig. 77 shows a simple and fairly effective ex- 



