
TRANSACTIONS OF THE SECTIONS. 131 
ventilation of mines. The other is that of the increased flow of water from a pipe, 
produced by giving a gradually widening form to its discharging extremity. 
_ A sketch of the apparatus is given in the accompanying figure, where A is a pipe 

which supplies the water to the nozzle B- for the jet, and C is a pipe which receives, 
at its narrow end, the jet from the nozzle, and on account of its gradually widening 
form, causes a suction capable of raising water by the pipe D. 
The various principles brought into action in this apparatus, have, as was stated by 
the author, been long known in hydrodynamics; but their combination in this form 
for use’ he believed to be new... A rush of water had been used previously in a some- 
what similar way in Italy to draw up and carry off the water of a marsh. In respect 
to the method there employed he had not been able to obtain full information; but - 
the description of it he had received led him to suppose that it was not so efficacious 
as the method which formed the subject of his communication to the meeting. 
On the Production of Cold by Mechanical Means. By W.S. Warv. 
To effect the purposes named in a preceding paper, Mr. Ward proposes a different 
method, and the substitution of the vapours of volatile liquids, such as sulphuric 
gether in place of air. He believed the theoretical results would be the same, and 
some sources of loss diminished ; but although he doubted whether either form of 
apparatus would be ceconomically efficient, he felt that interesting results would follow 
well-conducted experiments on the subject. 
On Telegraphic Time Signals. By Cuartes V. WALKER. 
The object was, to explain the arrangements that have been completed, as far as 
his part in them extends, for promoting the scheme of transmitting Greenwich mean 
time throughout the kingdom. On the 5th of August 1852, the first tume-signal passed ; 
and on August 19th, the clock at Greenwich, which originates the signals, having 
been brought to time, and the adjustment elsewhere having been completed, the 
sae transmission of signals commenced; in the first instance, to Dover, at noon, 
and at 4 p.m. Mr. Walker then described the apparatus constructed by Mr. Shep- 
herd, and erected at the London Terminus, by which the connexions are made. And, 
incidental to this, it is to be understood that in the galvanic-room at the Royal Obser- 
vatory is a set of ordinary sand-acid batteries (to be replaced ultimately by graphite 
batteries) ; one battery termination is connected with the earth, by means of the gas- 
pipes; and the other with a spring contained in Mr. Shepherd’s electro-magnetic 
clock. The Greenwich London wire also terminates in the same clock: and the 
connexions are such that, at the last second of the last minute of eack hour, this line- 
wire and the battery-wire are placed in contact for an instant; and, consequently, if 
the circuit is completed at the other end of the wire, whether at London, Dover, 
Rochester, the Strand, Lothbury, or elsewhere, a signal will pass every hour; and, 
when the circuit is left open, no signal will pass. To accomplish this, a train of 
_ wheels is connected with the rod of Mr. Carter’s large turret-clock, now erected over 
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