160 Scientific Intelligence. [Fey , 
ticians, as the author of the letter affirms, be not Fellows, the 
fault is not to be imputed to the Society. Every person who wishes 
to become a member of the Society must express his desire fo be 
so by presenting a petition signed by three members. If any ma- 
thematician of respectability does so, I think 1 can answer for the 
result; but if the mathematicians of England do not choose to. 
take such a_step, it would be very unjust to blame the Royal Society 
on that account. : 
V. On Ensuring the Attention of Watchmen. By Mr. R. W. 
Bauhard. 
(To Dr. Thomson.) 
MY DEAR SIR, 
In alate number of the Anrials of Philosophy you gave us a 
drawing of a machine or instrument to ensure the attention of 
watchmen. I hope I shall not be trespassing too much on your 
time and limits in sending you the enclosed sketch of what I think 
an improvement on Mr. Beaufoy’s plan, as it registers more effee- 
tually the time at which the omission did take place (supposing the 
watchman not to attend regularly), and is also better adapted to 
common use, as it only requires a common bell pull handle to be 
put in some part of the watchman’s round, which handle he is 
desired to pull once every hour, or oftener, if thought necessary. 
The machine itself may be placed in any part of the house, or other 
building intended to be watched, and communicating with the 
handle by means of a wire, as acommon bell. The enclosed plan 
consists of the watchwork of a common clock without the hands. 
Let B B B B (Plate XLII. Fig. 3) represent the face of the clock, 
with the drawing AAA for a dial on the front of it, on the 
periphery of which are 48 small wire pins made to slide easily 
into the holes, in Which they are fitted. On the upper part of the 
dial is a small mortise, a, in which a hammer, E, comes through 
at such a height that the dial and pins can pass under it. When 
not in action, the hammer is attached to the bar, f, and suspended 
to the two pivots, a, a.. At one end of the bar, is a lever, 4, to one 
end of which is attached the wire, g g, and to the other end the 
spiral spring, C, the use of which is to elevate the hammer, E, so 
that the pins can just pass under. If we now suppose the clock put 
in motion, one pin will be brought under the hammer every quarter. 
If the wire is now pulled, the pin will be driven down ievel with 
the surface, which will show that the watchman did his duty ; but 
if he should come either before or after the time, the pin driven 
either before or after the hour will show the time he pulled the 
handle. At the expiration of the watch, the dial is to be taken off, 
by taking out the pin, 4, and the pins that have been driven into 
the surface pushed out to their places again, I have sent a very 
imperfect sketch; but, such as it is, I hope you will see the idea 
, of it, and Remain, dear Sir, yours truly, 
R. W. Bauwarp, 
4 
