Makcu 28, 1907 | 
burnt would be 1-6 lb. per indicated horse-power with one 
ship, whilst the sister vessel would be “* gassing ’’ (we 
shall have to become reconciled to the objectionable term) 
with a ‘consumption of 1 lb. of coal per indicated horse- 
power per hour. Here is a saving of more than 50 per 
cent. in weight of coal carried, bunker space, time of coal- 
ing, and other subsidiary matters, amongst them money 
cost. At lower powers the figures bear approximately the 
same ratio. 
These are enormous strategical advantages, but the 
tactical benefits offered are hardly less pronounced. By 
means of profile views the author showed the gun 
emplacements of the two ships. With the usual two- 
chimney arrangement of the steam ship, there are four 
y2-inch guns placed in pairs in two barbettes at the ends 
of the battery, as is usual. These have arcs of train- 
ing, a few degrees before or abaft the beam respec- 
tively, whilst the weapons of a lighter nature can 
only fire on their respective broadsides. When we turn 
to the ship without boilers—the gas-engine ship—we find 
the space that would be taken in the other vessel by 
funnels, uptakes, &c., occupied by three additional barbettes 
placed en echelon, and each containing two 12-inch guns. 
There are also the two end barbettes with their four guns, 
as in the steam ship. These six centrally placed guns 
can be, moreover, trained on either broadside, so that, in 
an encounter between the steam ship and the gas ship the 
latter could bring ten 12-inch guns into action as against 
four of the former vessel, supposing the encounter to be 
broadside on; or, to put the case another way, the gas ship 
could fight a steamship on each broadside, and have a 
superiority over her enemies of two 12-inch guns. With 
secondary armament the problem is more complicated, and 
could hardly be explained without diagrams. 
What, it will be asked, are the defects of these quali- 
ties? and an answer can only be given by the light of 
experience—an experience only likely to be gathered by 
steps. The marine steam engine has been brought to such 
a state of efficiency that its performance can be prac- 
tically depended upon; this is not the case with the pro- 
ducer gas engine. There are many things to find out yet, 
the problem being more complex from the combination of 
mechanical and chemical sciences that have to be applied. 
With gas engines afloat—a very different thing from gas 
engines ashore supplied from a central source—one hears 
of the explosive mixture failing, from unexplained 
causes, and the engines stopping without warning, and 
there are details of -working connected with ignition and 
other points which have yet to be perfected. For much 
the same reason that many naval engineers prefer 
hydraulics to electricity for working armaments, steam is 
likely to be preferred to gas for propelling battleships. 
Which will ultimately survive time will show; in the 
meantime, it may be said Mr. McKechnie has worked out 
a very strong case for gas. 
The remaining paper taken on this day was by Mr. Simon 
Lake, who dealt with the subject of submarine boats. 
The type of vessel the author advocates is fairly well 
known, its most striking characteristic being that it is 
fitted with wheels so that it can travel along the bottom 
of the sea. The paper gave an interesting account of 
some of Mr. Lake’s adventures in his ingeniously devised 
craft. 
On the second day of the meeting Mr. W. J. Luke, of 
Clydebank, read a paper in which details of certain points 
in the construction of the new big Cunard ship Lusitania 
were set forth. The chief point was the application of 
high tensile steel in the upper part of the hull structure, 
a detail of shipbuilding design which possesses definite 
advantages, seeing that the hogging stresses are more 
serious than the sagging stresses, and therefore tension is 
of high importance for the upper member of the girder 
formed by the hull structure. The evolution of the 
modern cargo steamer was the subject of a paper by Mr. 
S. J. P. Thearle, of Lloyd’s. It was a contribution that 
will be of value in the Transactions of the institution for 
future students of the history of shipbuilding. Cranes for 
shipbuilding afforded a subject of practical interest for 
Signor C. Piaggo. 
The two papers that were read at the evening meeting 
of the same day were both of interest and importance. 
NO. 1952, VOL. 75] 
NATURE 
373 
They described two forms of instrument for measuring the 
power given off by turbines. The author of the first 
paper was Mr. A. Denny, and of the second Mr. J. H. 
Gibson. As is well known, the ordinary steam-engine 
indicator, by which horse-power has been measured since 
the days of James Watt, is useless for application to 
turbines, because there is no reciprocating motion with the 
latter. This has been a serious obstacle in the path of ship 
designers, but it appears to have been overcome by taking 
indicators of the torsion of the shafting through which 
power is conveyed from the turbine to the propeller. In 
both the instruments described by the authors of the two 
papers recourse is had to this means, but the method of 
recording is different. In the Denny and Johnstone torsio- 
meter is an electrical method in which a telephone is used, 
whilst in Mr. Gibson’s instrument recourse is had to a 
flash of light deflected by a mirror. The details by which 
these processes are made practical have been worked out 
in each case with great ingenuity, but it would be difficult 
to make them clear without illustrations. It may be 
pointed out, as Lord Glasgow stated at the meeting, that 
the successful application of these instruments will solve 
a problem that the elder Froude worked out with much 
enthusiasm during the later years of his life, though with 
very partial success. A paper on propeller struts, by Mr. 
G. Simpson, was of purely professional interest. 
One of the most interesting papers of the meeting was 
Sir William White’s contribution on experiments with Dr. 
Schlick’s gyroscopic steadying ‘apparatus. This paper is 
of such interest that we propose to deal with it separately. 
Its full comprehension, however, involves a knowledge of 
the principles set forth in a paper read by Dr. Schlick a 
few years ago, Sir William having thought it unnecessary 
to go over the same ground again. 
The other papers read were on the approximate formule 
for determining the resistance of ships, by A. W. Johns; 
on the application of the integraph to ship calculations, 
by J. G. Johnstone; on the prevention of fire at sea, by 
Prof. Vivian B. Lewes; on modern floating docks, by 
Lyonel Clark; and on some phases of the fuel question, 
by Prof. Vivian B. Lewes. 
The institution will hold a summer meeting in Bordeaux 
towards the end of June. 
TICKS AS TRANSMITTERS OF DISEASE.* 
M ANY statements are found in medical works as to the 
local poisonous effects of tick bites, but these are of 
small importance compared with the diseases inoculated by 
ticks. Until a year or so ago ticks were only known to 
transmit one kind of disease, and this was confined to 
the lower animals. Of these diseases, ‘‘ Texas’ fever in 
cattle may be regarded as the type. These diseases, which 
are met with in cattle, horses, asses, sheep, and dogs, ‘are 
due to parasites which attack the red cells of the blood. 
The parasites are characterised by their pear shape, and 
hence were originally called Pyrosoma; but this name has 
now generally been replaced by Piroplasma, and the in- 
fection by these parasites is known as piroplasmosis. 
Smith and Kilborne in America, by their classical re- 
searches, first established the fact that Texas fever in 
cattle was transmitted by ticks. We may consider the 
mode of transmission somewhat more closely. Ticks in 
their life-history go through the stages of eggs, larva, 
nymph, and adult. In the case of transmission of malaria 
by certain Anophelines, we know that the adult mosquito 
when it has fed on the blood of a malarial patient can 
transmit the disease again after the lapse of ten days, 
more or less, to a healthy person. Very different, how- 
ever, is the mode of transmission of piroplasmosis by ticks. 
Smith and Kilborne showed that Texas fever was trans- 
mitted from the sick to the healthy animal, not by adult 
ticks, but that it was young ticks hatched from the eggs 
1 ** Scientific Memoirs by Officers of the Medical and Sanitary Depart- 
ments of the Government of India.’’ New series, No. 23. 
“The Anatomy and Histology of Ticks.” By Capt. S. R. Christophers. 
Pp. 55+plates. (Calcutta: Office of the Superintendent of Government 
Printing, 1906.) Price 4s. 6d. 
Memoir xxi. of the Liverpool School of Tropical 
tember, 1906. Pp. xiv+113+plates. 
Price 7s. 6d. net. 
Medicine, Sep- 
(London: Williams and Norgate.) 
