492 
FOREST AND STREAM. 
[Dec ly, 1903. 
Although, as stated, this is not fee be a treatise, in^any,... 
scientific sense of the word, on the gasolene engine, 
it does not seem out of place to describe, for the bene- 
fit of those who may not be thoroughly familiar with 
the subject, the general nature of the operation of these 
engines and their manner of installation. 
The motive power is an explosive mixture of gaso- 
lene vapor and air in proper proportions, which is 
ignited at the proper time in the cylinder space general- 
ly by means of an electric spark. BeuEene is midway 
between gasolene and kerosene in the distillation scale, 
and is commonly known in the oil trade as naphtha, 
the grade used for gasolene engines being usually about 
72 degrees Beaume scale. 
The engines are divided into two distinct types — the 
two-c3'cle and the four-cycle. In the former the piston 
receives an impulse once in every two strokes or each 
complete revolution, while in the latter the explosions 
occur every fourth stroke or every second revolution. 
In the two-cycle typt the crank space is enclosed in an 
air-tight case, this space as welLas the cylinder being 
connected to the air and fuel supply. On the up stroke 
the piston suction draws air into the crank space 
through a vaporizer, in which it is charged with gaso- 
lene vapor, the degree of saturation being regulated by 
a needle valve controlling the gasolene opening. This 
charge is compressed by the succeeding down stroke, 
and by means of a port uncovered just before the end 
of this stroke is allowed to rush up into the cylindef 
space, there to be again compressed to from 75 to 85 
pounds by the piston during its next up stroke, and 
exploded just before the end of this stroke. Thus dur- 
ing each up stroke one charge is drawn into the crank 
case and another is compressed in the cylinder and 
ignited, while during the succeeding down stroke the 
ignited charge Is expanding and doing work, and the 
new charge after being compressed in the crank case, is 
transferred to the C3'linder preparatory to compression 
and ignition, the burnt gases having escaped through 
an exhaust valve just before this. In the four-cycle 
type the crank space is not enclosed in an air-tight 
case, and the operations of drawing the charge, corii- 
pression, ignition, expansion and expulsion have to be 
carried on in the cylinder itself. During the first down 
stroke the charge is sucked in, compressed during the 
succeeding up stroke and ignited, expanded during the 
following down stroke, expelled during the next up 
stroke, after which the cycle repeats itself. 
Both these types of engines have their exponents in 
well known machines that have been on the market long 
enough to demonstrate their reliability, and opinions 
seem divided as to Avhich of the two is- the better, tak- 
ing everything into consideration. Other things being 
equal, it appears that where saving in weight alone is 
the main object the two-cycle with its impulse every 
revolution would be preferable; but the gain in power 
per cylinder is not what would be expected, as the com- 
pression and consequent M. E. P. is not so , great as 
in the four-cj^clo. Moreover, the enclosed crank space 
adds more weight to the engine, thus further reducing 
the advantage. 
The matter of weight for a given horse-power varies 
very considerably among the different designs made in 
this countr3% some engines being more particularly 
adapted to racing and others to general work; some 
makers make engines of different weights to meet the 
various conditions. Foreign motors, as a rule, are 
lighter than our OAvn, approaching more nearly the 
automobile scale of weights. Personally, I think that 
the reasonably heavy engine is a much healthier de- 
velopment than the extreme racing machine. It seems 
that we save enough in dispensing with boiler, stack, 
condenser, auxiliaries, piping, etc., to make a decent 
allowance to engine weight possible. 
As the installation of the fuel tank and supply pipes 
has much to do with the safety of ihe vessel, the most 
important points to be observed will be noted briefly. 
Tanks are properly made of heavy copper, "with riveted 
and soldered joints. All connections for fittings should 
have flanges on inside and outside to prevent tearing 
the copper. A number of baffle, plates must .be fitted 
to control the motion of the oil when the vessel 'is in 
rough water. The tank is generally located in a peak 
compartment, but occasionally near the center of the 
vessel. In either case, the space in which the tank is ' 
placed should be carefully ceiled, and the tank made an 
accurate fit by peining the sheets to shape in place be- 
fore assembling them; this prevents any bulging in 
and out of tank sides, which is honnd tn make leaky 
joints eventually. The tank compartment generally 
has a water-tight bulkhead on each side of it. and in 
many instances is flooded by having a number of holes 
fhrough the planking in the region of the waterline. 
An alternative to flooding the tank compartment is to 
work a flat across underneath the tank, this and the 
sides of the compartment being sheathed with copper 
to a considerable height, thus forming a pan, which is 
given an overboard drain by pipes carried down and 
out through the side. The compartment may also be 
flooded if desired. In both methods the prime object 
is to provide an escape overboard for- the gasolene in 
case of leakage or accident. As in any event the tank 
bottom should not be lower in the vessel than the 
vaporizer in order to secure a .flow even with a small 
quantity of oil in the tanks, possibly the method in 
which a flat is Worked under the tank is the more 
logical, particularly as it should . result in absolutely 
freeing the bilge from any danger of gasolene vapor or 
fluid. The supply pipe from tank to vaporizer should 
have a cut-off valve just outside tank, and before enter- 
ing vaporizer. The pipe should run directly down from 
the tank, out through the planking close in 'to the keel 
and then direct to the location of the vaporizer, where 
it will re-enter the hull. Naturall)', extreme care should 
be taken in making up all joints -in this piping, and a 
careful test should be made of the M'hole system when 
completed. The tank space, as --yvel! as engine room, 
should be well ventilated, As gasolene vapor is heavy, 
any system by which the air>, in- thei bottom of the 
compartments is sucked but '^vould-'beithe ;most effec- 
tive. This would apply particularly to'-installations on 
vessels of som.e size with enclosed engine rooms. ' If 
the pre^autiong suggested ar^' tel^^n, danger (rgisn 
Eight-Cylinder, Two-Cyole, 120 H. P. Leighton Engine. Plate 1. 
110 H. P„ Sii^fCjdinder, Four-Cycle Standard Engmfe^ Starboard Side. Plate 3. 
110 H. P., Six-Cylinder, Four-Cycle Standard Engine Port Side. Plate 3. 
explosion of gasolene should be very small, and has 
been found so in actual practice, nearly all accidents be- 
ing directly attributable to carelessness in installation. 
The charge is, in most instances, ignited by an elec- 
tric spark, as before stated, this spark being generally 
produced by a break in a low potential circuit of prim- 
ary cells or a magneto machine, thus causing an in- 
duced spark of high tension in the cylinder space by 
means of a regular jump spark arrangement with 
Ruhmkorff coil, one terminal being grounded to the 
engine casting and the o';her connected to a well in- 
sulated electrode projecting into the cylinder space. 
The timing of the spark in the stroke effects the speed, 
and in all properly designed engines is capable of- con- 
siderable adjustment. In all cases, except when start- 
ing, it must occur before the end of the compression 
gtrgk?, and for ij^^xinauw speed tl^? Uighest presgvirf 
should be reached just as the piston starts on the down 
stroke. At higher speeds the time of sparking must 
be set earlier in the stroke than at the lower, to allow 
suflicient time for thorough ignition. In some installa- 
tions a dry battery is used for the initial sparking, and 
when the engine is once started the battery is cut out 
and a magneto driven off the engine thrown in, thus 
reducing the drain on the batteries. The electric wires 
must not be run low in the bilge, Avhere they would be 
aft'ected by dampness or water, or where a spark from 
a bad connection might ignite escaped gasolene vapor. 
The batteries, terminals, magneto and all electric con- 
nections must be well protected from dampness and 
spray tc insure proper working. All wire connections 
to terminals, as far as possible, should be soldered, and 
binding screws should have locknuts to prevent them 
