182 REPORT—1857. 
— 
other of the vessels ; and alluded also to several recent cases of collision, in which it 
was subsequently shown that one of the vessels had seen the other in sufficient time, 
and at a sufficient distance, to have averted the calamity had the means been at hand 
of instantly giving warning of the danger in such a manner as to have attracted the 
attention of the people on board the approaching ship. ; 
Captain Leach suggested that for this purpose every sea-going vessel should be 
compelled to carry brilliant percussion lights, to be used as “ danger signals,” which 
would ignite on being struck against any hard substance; and that the officer of the 
watch, or other person in charge of a ship, should be held criminally responsible that 
these signals were ready for instant use in lockers placed on deck in suitable situations. 
He pointed out, that, besides indicating danger, these lights, by the use of four dif- 
ferent colours, might be made to show whether a vessel was at anchor or in motion, 
and her course upon any one of the eight principal points of the compass ; or, if a 
more simple code of signals was considered desirable, that two coloured lights, and a 
white light, used singly, would be sufficient to make known the tack on which a ship was 
steering, or whether she was stationary ; and observed that such lights, which would 
not be costly, and would be always at hand in case of danger, might be made suf- 
ficiently brilliant, and of such an illuminating power as could not fail to attract the 
attention of the helmsman, even supposing the look-out to be asleep or otherwise 
neglecting his duty. 
It was not proposed to interfere with the existing lights carried by sea-going ves- 
sels, but to use the percussion lights as ‘‘ danger signals” only. 
Captain Leach also recommended the use of percussion lights by railway companies, 
and drew attention to several cases of collisions on railways which could not have 
occurred had the guards of the disabled trains possessed such a means, in addition to 
their ordinary signal lamps, of making the drivers of the following trains aware of their 
danger. 
a 
Early Methods of Propelling Ships. By Joun Maccrecor, M.A. 
Almost every method of marine propulsion has its type in means employed by sea- 
water animals, and among these may be specially noticed :— 
Ist. Arms, legs, fins, tails, paddles, membranes or cilia, with a reciprocating 
motion feathered in the water, as by water-beetles, amphibious animals and fish. 
2nd. Water forced through tubes, as by the cuttlefish and paper nautilus. 
3rd. Creeping motion by whelks. ‘Sooping” motion by the Pedipes. Creeping 
and swimming combined by the Lepidosiren. 
4th. Screw propeller motion, by the Paramecia vulgaris (in which an undulation 
or protuberance moves round its oval-shaped body spirally*). 
5th. [Propulsion by sails +, as by the “ Portuguese man-of-war” and aquatic birds. ] 
Marine propulsion methods may be classified according to 
The power used and machinery employed. 
I. Muscular power, (A.) of men, (B.) of animals. 
II. Expulsion of gas or water against air or water. 
III. Springs, weights, gunpowder, capillary attraction, wind and other motions, 
IV. Endless chains and revolving wheels. 
V. Submerged propellers. 
(a.) Feathering oars, collapsing vanes and sculling oars. 
(b.) Feathering paddle-wheels and screws. 
VI. Submarine vessels. 
VII. Steering apparatus and directors. 
(A.) Propulsion by muscular power of men. 
The methods arranged progressively. 
(1.) Swimming without artificial aid. 
(2.) Webbed fins or hooks on the limbs, as proposed by Borelli (a.p. 1683), to 
enable the diver ‘to swim like a frog or creep like a crab}.” 
* A half-turn screw-like movement in the gauze wings of an Australian fly was depicted : 
in the ‘ Illustrated London News,’ August 15, 1857. ~ a 
+ This paper does not include propulsion by sails. che! s 
+ See ‘Marine Propulsion,’ p. 15. (This book is an abridgement of the specifications of 
