588 Transactions. — Miscellaneous. 



observed in this district — by simply altering and regulating the 

 admission of cold or cooled water into the flask or retort, 

 and altering the length and relative positions of the glass 

 tubes. 



I have adopted 27in. as the length of the glass tube, as 

 this represents about lib. pressure to the square inch; but 

 the longer the tube the better the influence and efiecfc of 

 the difference between the specific gravity of cold and hot 

 water, the water boiling under pressure, and the ascending 

 steam-globules will be demonstrated ; and the greater the 

 pressure the stronger will be the geyser-action, as explained 

 in my original paper. 



I would also mention that the flask need not necessarily 

 represent a cavern or cavity, for it w^ill act equally well when 

 filled with pieces of pumice or stones, thus representing broken 

 rubbly ground, where water can lodge and accumulate from 

 any source or direction. 



I will now endeavour to describe how some phenomena 

 may be demonstrated. 



First, fill the tray (B) with water so as to cover the top of 

 the glass tubes, say, -lin. above them; light the spirit-lamp (F), 

 and set it so that it will cause the water in the flask to rise to 

 a temperature of, say, 3° or 4° above boiling-point. Then, to 

 illustrate — 



1. .1 Hot Sjjring (say, 140° to 180°).— Set the two glass 

 tubes C, D, to the same length both at the top and bottom, 

 leaving both fully open. Aftt-r a short time, when the water 

 of the flask reaches a temperature of, say, 60° to 100° above 

 the temperature of the water in the tray B, introduce a piece 

 of sponge on the end of a thin wire into one of the tubes (say 

 C) nearly to the bottom ; then draw it smartly up : this will 

 cause the hot water in the flask to fill the tube C, while the 

 cool water in the tray will run down D. This will, owing to 

 the difference between the specific gravity of hot and cold 

 water, destroy the hydrostatic equilibrium ; and, by putting a 

 little sawdust in the tray, it will be seen that the hot water 

 will continue to ascend in C, and the cold to descend in D, fast 

 or slow in proportion to the quantity of heat generated by the 

 spirit-lamp. The ascending hot water, on being exposed in the 

 large cooling-surface of the tray B, will naturally lose its tem- 

 perature, re-enter the tube D, descend into the flask F, get 

 reheated, and ascend C ; and this action will continue as long 

 as the heat and the water last. If it is desired to change the 

 action from one tube to the other, it is only necessary to 

 repeat the action with the sponge in the opposite tube, and, 

 when once the trend of the hot water is established, the re- 

 verse action will be caused and continue as before described, 

 thus illustrating that the heat generated by the spirit-lamp 



