i 7 6 
Offensive and Defensive 
[March, 
destruaion, he has only brought down the history of 
torpedo-boats to the American inventions of Messrs. Her 
reshoff, of Rhode Island, U.S. A., whose novelty consisted 
chiefly in its coil boiler, by which a good working pressure 
can be obtained within a few minutes of lighting the fire, 
whilst the fire and the boiler can be blown off in a few 
seconds. But this advantage has been comparatively nulli- 
fied by the faa that the Thorneycroft and Yarrow boats can 
be supplied with steam from the main boilers of the ships 
to which they are attached. Thus in a late experiment at 
Stokes Bay a Thorneycroft (No. 56) was supplied with 
steam from the Lightning, beginning to move in 9 minutes 
« seconds, with a pressure of 60 lbs., whilst the Herreshoff 
got under weigh in 8 minutes 2 seconds, with a pressure of 
qo lbs. • but after trial on the measured mile the former 
attained a speed of 14-168 knots, and the latter only 12-972 
knots. It was at this trial that the Herreshoff boat ran into 
the Manly tug, her sharp nozzle going completely th ™ugh 
her side, happily above the water-line ; and although the 
Herreshoff' s bow was stove in, owing to her five water-tight 
bulkheads, she floated easily, the breaking of her glass 
steam-guage being the only damage done to the machinery 
bv the concussion. _ , ~ 
Messrs. Yarrow are now building, for the French Govern- 
ment boats to go backwards and forwards at the rate ot 
'5 knots per two hours,-..,., an average of 18 knots either 
way, what is lost in going ahead being gained in going 
astern. It will be interesting when this guaranteed rate is 
a *The same builders are also building a larger class of 
torpedo vessels which will supersede the Lightning class 
(first class), measuring 84 feet in length, with a beam o 
7 feet 6 inches. The new vessels are to be constructed of a 
more powerful type, viz., 100 feet in length, with beam of 
12 feet 6 inches, and they are to carry enough coal to enable 
them to steam 1000 miles. 
Some boats have also been tried, made by Messrs. Mauds- 
lav Sons, and Field, of plates of manganese bronze, whose 
thickness does not exceed from one-eighth to one-sixteenth 
of an inch : they are not quite so stiff as steel plates of the 
same thickness, and vibrate when the pulsations caused by 
the propeller are isochronous with those produced by the 
spring of the boat going at from 10 to 12 knots. This vi- 
bratory quivering, however, disappears when a rate 0 
16 knots is attained. . , 
It is greatly to be hoped that these inventors, in attempt- 
ing to obtain various improvements in speed and strengt 
