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TRANSACTIONS OF THE SECTIONS. 219 
would have acquired a velocity of 32 feet per second. Let us place the cover on the 
cylinder, and lift up the hammer as before, only, instead of allowing it to rise up into 
the atmosphere until its velocity and force were counteracted by gravity, let the steam 
be entirely withdrawn from below the piston, and a supply introduced upon it. 
That which has the power of putting it in motion has also the power of stopping it, 
and of causing it to return with the same velocity, aided also by that which is due 
to its gravity ; and it will be evident that, by the time it has reached the object it is 
intended to strike, it must have acquired more than 32 feet per second, although the 
space moved through is only one foot. So much for the effect of the blow. Now 
for time. We have assumed that, when the retarding force was employed upon the 
piston, it was moving with a velocity that would have carried it 16 feet, and it was 
returned with a still greater velocity by having the weight of the hammer with it 
instead of against it; so that the time must be considered as that which it would take 
to rise one foot at such a velocity as would, if the motive power were withdrawn, 
have sufficient momentum to carry or throw it 16 feet, and the time in returning 
could not be more than the difference in time of a body falling 16 and 17 feet. The 
double-acting steam hammer, working with such relative force and weight, would 
give the same effect as the single-acting hammer of 16 feet range; but as to time, 
there would be about 30 blows of the double-acting hammer to one of the single. 
This hammer is also capable of giving very light blows as well as very heavy ones ; 
and it can be made either single or double acting by the circular valve, which works 
longitudinally in its chamber. A double hammer of 20 cwt. at work in Sheffield, 
has attained 200 blows per minute ; and hammers of 10 cwt. have given 250 blows 
per minute. These hammers are under the most perfect control of the workmen, 
and can be worked as slow as necessary. 
On a Plan for giving Alarms in Passenger Trains. 
By J. O'NEILL. 
This invention consists of an iron bar extending under each carriage, and suspended 
on a pin a little from the centre, so as to make one end heavier than the other. 
The heavy end is securely held in a bridle, by a hanging latch at the end of the 
carriage. 
The light end also passes through a bridle at the other end, and has a tongue 
which draws out from the bar and reaches under the latch fixed on the next carriage. 
By disengaging any of the latches, the heavy end falls; and the light end, in 
rising, throws up the next latch, and so on to the guard’s van, where it rings an 
alarum. 
A chain or wire, fixed to the latch and brought into the carriage, gives each pas- 
senger, in the event of danger, the means of giving a signal to the guard; anda 
duplicate set of bars, on the other side of the carriage, enables him instantly to com- 
municate with the driver, if necessary. 5 
The end of each tongue has a rising point, riveted loose ; so that the porter, when 
coupling the carriages, could put it in position for disengaging the latch, in case the 
carriages should become detached by the breaking of the coupling chains. 
As the bars are not connected, any number of carriages can be taken off or put 
on at a station by merely turning the loose point on the end of the tongue up or 
down. 
On the Gresham Buoy, for recording the Loss of Missing Ships at Sea. 
By James Otpuam, C.E., Hull. 
The object of this paper is to point out a mode by which a record of the loss of 
ships at sea may be attempted, where otherwise no account would ever be obtained. 
It is proposed that every sea-going ship, of whatever description, and particularly 
those carrying passengers, shall be provided with one or more copper buoys, bearing 
the name of the vessel and the port to which she belongs; that they shall have an 
Admiralty mark, and a Board of Trade number. 
The “Gresham Record Buoy” (so-called from having been suggested by John 
Gresham, Esq., of Hull) would be provided with a chamber, and a small spring valve 
