124 History of Mechanical Inventions and Useful Processes . 
tions are double-rivetted as in Fig. IS, the rest having only a 
single row. When a rivet breaks, it is replaced by making an 
opening in the seam, of sufficient size to allow the hand to re- 
place not merely the rivet that is broken, but those taken out to 
form the opening. When the rivets are fixed in the holes, 
they are rivetted by placing them upon a flat bar of iron, in- 
troduced in the entrance of the hose. The rivet and burr 
should both be of wrought copper, and not of different mate- 
rials. Tin rivets, for example, with copper burrs, in conse- 
quence of the galvanic action, will destroy the leather in a few 
months. 
The method of connecting the hose is shewn in Fig. 14, 
•where A is the female part of the swivel joint attached to the 
hose by the female screw cc, and prevented from collapsing by 
the brass ring d , within it. On the outer side of this screw is 
a groove, hh, on which the swivel ring a revolves ; this ring 
being fixed to the female connecting screw, B, by means of 
rivetting over the end of it at f The male screw C, is attach- 
ed to another portion of hose in the manner already described. 
The different pieces of leather that compose the hose are 
connected by a spiral joining of double rivets. 
For farther information respecting this invention, see the 
Transactions of the Society of Arts, vol. xxxviii. p. 102., from 
which the preceding account has been abridged. 
5. On forming a Communication with the Shore in Shipwrecks, 
and on instantaneous escapes in cases of Fire*. By Mr 
John Murray, Lecturer on Chemistry, &c. 
The invention of Captain Manby, beautiful and valuable as 
it is, is not always available. The rope frequently snaps, and 
* An apparatus for saving lives in cases of shipwreck, by Mr H. Trengrouse, 
has been described in the 38th volume of the Transactions of the Society of Arts, 
p. 161. The projecting force used in the apparatus, is a rocket , and it was found 
that a rocket of 8 oz., with a mackerel line attached to its stick, ranged to the 
distance of 180 yards , and that a pound rocket in similar circumst£yices ranged 212 
yards. The rocket is placed in a copper instrument at the end of a musket 
charged with a small quantity of powder without wadding, for the purpose merely 
of directing and igniting the rocket. The rocket, when lighted by the powder, 
burns for a few seconds before it acquires sufficient momentum to quit its situa- 
tion, during which time the combustible would be ejected into the barrel of the 
