Dec. 19, 1903.] 
FOREST AND STREAM. 
49S 
5C(^uE Feet. 
Speed Launch Adios. — —Plate 4. 
S PEED LAUNCH ST^NDKRO . 
in which the electric spark is not used as the means of 
ignition, a tube heated by a flame to the proper tem- 
perature starts the combustion, this method being em- 
ployed by at least one well-known maker. Some launch 
owners prefer to use a storage battery instead 'of the 
customary dry cells, and one of the 1,000 mile automo- 
bile batteries will last the greater part of a season for 
this purpose with ordinary use. By having a spare bat- 
Speed Launch Standard. Plate 5. 
which revolve the individual blades on their axes. The 
fact that f^the'-en-gine must be run continuously during 
the changing from going ahead to reversal makes it 
evident that a method of governing should be provided 
to prevent racing during the change in load. This con- 
tinuous running of the engine during short stops, when 
making landings, going alongside other boats, and, in 
general, when quick and positive starting is required, is, 
as a rule, quite objectionable, owing to the noise and 
vibration usually caused under these conditions. 
The speed of the engine is altered by changing the 
timing of the spark, as already stated, and also by 
throttling the gas supply. In all good designs both 
means of speed control are provided, and the throttle 
in addition is actuated automatically by a governor 
driven off the engine to prevent racing under release 
from load when stopping or running in a seaway. By 
a combination of these methods, and by the use (^f 
warm air, a large range of speeds and a considerable 
variation in the consumption of gasolene per H. . P. 
hour is possible. Under the best ordinary conditions, 
when the gasolene vapor is in the proper proportion', 
I he consumption does not vary greatly from one pint 
per horse-power hour, and_ this is the figure generally 
used in calculating tank capacities. 
The heat produced by the high temperature of tic 
products of combustion is drawn off by circulating' 
water from the sea driven by a pump from the engine, 
the cylinders being well jacketed for this purpose. In 
some cases after passing through the jackets this water 
is discharged directly overboard, and in others it enter'- 
the exhaust pipes and passes out with the consumed 
gases. The latter method is preferable, lovfering as u 
does the temperature of the exhaust line and reducing 
the back pressure, and having also the effect of seem - 
ing a less noisy exhaust. Some form of muffler tan'\ 
or expansion chamber is generally fitted in the exhavist 
line to deaden the soimd of exhaust: diaphragms ol 
different designs are sometimes introduced in these 
tanks to assist in the muffling process, but they have 
Speed Launch Adios at 23 Miles an Hour. Plale 8. 
tery on hand of this description, there seems less chance 
of trouble than with the primary cells, which have a 
way of running down unexpectedly. In any case there 
should always be a reserve to fall back on in the event 
of a good spark not being produced. 
In practically all the gasolene engines_ now on the 
market, with one notable exception, an initial charge 
must be drawn into the cylinders by cranking the en- 
gine over- by hand before an explosion will be pro- 
duced and rotation commenced, and when the engine is 
so started it runs continuously in one direction, reversal 
being impossible. Accordingly, to make it possible to 
stop and rev^erse the propeller, either the connection 
between the engine and the wheel must be by gearing, 
or a feathering blade must be used in which the pitch 
can be altered at will by the engineer. The first method 
is the most frequently used perhaps, and by many is 
considered the more reliable, S'everal very substantial 
ana positive friction gear clutches being on the mar- 
ket, so arranged that by manipulating a lever the tail 
shaft and crank shaft may either rota,te as one or in 
opposite directions, or the tail shaft may remain idle 
while the engine turns over. Several very simple and 
effective feathering wheels are on the market also, and 
give excellent results, the pitch of the blades being 
altered at will from a maximurn go-ahead pitch, through 
zero, 'to a maximum backing pitch with the same direc- 
tion of rotation of the shaft. The shafting in such cases 
is hollow, and a rod >yjt^^iJi it controls Jever§ gi? thf 
