HOT WATER, 3138 
siphon, by taking a piece of lead pipe, say of half an inch 
bore, and four or five feet long, bending it like a siphon, 
but one leg a good deal more bent than the other, in order 
to.give the descending water. time.and space for giving out 
its heat ; and then, filling this tube with water, and placing 
one hand on each end to retain it full, immerse the extre- 
mities in a pot of water over a fire, as represented in the 
annexed diagram. Supposing the water of 5, g. 84 
a uniform temperature in both legs of the  :: .. 
siphon, no circulation would take place ; but 
supposing it to cool sooner in the long leg 
a@ than in the short leg 4, then the equilibri- 
um would be destroyed, and. the water in 
the long leg a would descend, and draw up 
water through the short leg 6; and this cir- 
culation would continue as long as the water 
c was maintained at a temperature above 
that of the surrounding atmosphere.” 
Mr. Kewley’s adaptation of the siphon is one of the 
simplest and most efficient that has been proposed. In 
Fig. 35, a c e ate the two legs of a siphon, through the 
upper of which the heated water ascends, and by the lower 
descends. Immediately over the descending bend, a pipe 
connected with an air-pump is inserted, in order to fill the 
pipes, or remove the air which collects in the superior 
limb. Instead of the air-pump, a funnel with air-tight 
Fig. 35. 
