and its application to Fire Alarms. 81 
in the figure, reversing at the same moment the three-way valve 
by asimple arrangement. The water which before entered now 
begins to flow out. The valve v’ opens and admits air. The 
float falls until at last it rests on the tail piece t/ of a correspond- 
ing short lever below, by which the heavy ball is raised to the 
perpendicular and thrown over on the other side, reversing the 
three-way valve again, so that the water enters. The water, on 
entering each time, condenses the air into the reservoir R, from 
which a valve prevents any return. This process continues till 
the air in R has reached a condensation equal to the pressure of __ 
the column of water in the pipes. Any loss of pressure from cd 
either leakage or use, is at once supplied by the action of the gene- 
ratorG. All the paiis in the generator liable to oxydation, are 
made of brass. 
The reservoir R may easily contain several hundred charges 
for the cylinder C, so that if the water should be withdrawn from 
the pipes for a day or more, no interruption in the means of alarm 
would take place. With a vressure of two or three atmospheres, 
such as can be obtained from <he Cochituate water in the lower 
part of Boston, a cylinder, C, of only two or three inches diame- 
ter, applied directly to a hammer as above, would give all the 
power which could be desired for the largest bell, without any 
limit as to the number of strokes, or necessity of winding. The 
electro-magnet m’, armature and catch c, on which the corres- _ 
ponding part of the falling arm rests, when raised from the posi- 
tion in the figure, will be easy recognized. When the armature _ 
1s attracted to the magnet the falling arm drops, and the foot, a, 
adsnes a pin on the sliding valve aud throws it back, admitting 
tae air into the cylinder. The cam and projection on the end of 
hg piston rod, respectively reverse the sliding valve, and raise the 
long arm b of the falling lever, at the end of the stroke. In the 
apparatus represented, the generator G must, of course, be placed 
ina low situation, such as a cellar, and out of the reach of frost. 
he air whistle, operated by hand, was proposed a year ago in 
Boston as a means of alarm. Its efficiency for this purpose can 
hardly be overrated. The simple mode of connecting it with the 
Telegraph, represented in the figure, has been proposed by Mr. 
Farmer. he air valve v” is operated by a rod, attached to the » 
armature lever of the electro-magnet m, which is actuated by a 
local battery connected with the Telegraphic circuit. ‘The same 
object may be accomplished, without a local battery, by a little 
falling lever and air engine apparatus. Two or three air whistles 
; tge size in a City, would be almost sufficient of themselves 
ot a System of Alarm. ee 
The use of the water meter of Mr. Huse, as a source of power 
for striking the bells, has suggested itself, and has also been espe- 
cially brought to my notice by Mr. Joseph M. Wightman of Bost 
ND Series, Vol. XIII, No. 37.—Jan, 1852. 
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