Evening star., 1902-02-13
High Power Engines.

At a meeting Of the Glasgow and West
Scotland Technical College Scientlhc So
ciety in November last Mr.. A. Rollason or
Nottingham read a paper on High Power
Gas which has excited widespread interest
on both sides of the Atlantic.
The author began by pointing out that
the working capabilities Of gas engines
have considerably increased In recent years,
SO that motors of more than 100 horse
power are now quite common and in daily
use. running satisfactorily and comparing
favorably in economy with the highest class
Of steam engines. He went on to say that
In this country the largest engines which
have been at work for any length of time
Indicate about 600 horsepower. On the
continent, however, sizes up to 1000 horse
power are at work and giving fairly good
results. There are, both in this country
and on the continent, fifteen well-known
firms making engines or over 2oO Indicated
horsepower.
The development Of these large powers
has not been attained without considerable
difficulties having to be overcome; but these
having been surmounted and the conditions
understood there is only the thickness of
the cylinder walls. which limits the guam
tity Of heat passing through the metal to
cylinder. Multiple cylinders. however, can
be used to give any desired power.
All the high-power engines with one ex-
ception, work on the lotto" cycle; and all
with two exceptions retain the hot products
of the previous explosion which are left in
the clearance space or combustion chamber
these products mixing with the new ex
plosive charge taken into the cylinder on
ferred to, while the lotto" cycle has been
retained, pump has been added to posi-
lively displace and clear out these products.
There are thus two distinct types Of en-
gineS for OBSERVATION-DISCLOSURES and nom
scavenger.
AS early as the year 1850 the late Sir VIII
liam Siemens described and claimed the
process of scavenging by passing a current
80 oNv. fnor Ind -
gas engine at the completion OF the effect
I've stroke. Since then many inventors
have attempted to solve this problem; but
1t was not until the year 1892, at the Crys-
tai Palace electrical exhibition, that an en-
gne with simple and effective scavenging
arrangement was first shown working.
The author expressed the opinion that
from an economical standpoint, all large
engines should be constructed to work with
fuel gases, as these usually contain from
sc to 20 per cent Of non-combustible mat
ter He showed the advantages of scav-
enging out the burnt products by a COM
parison Of the results obtained in engines
actuated by the same gas at the works Of
Messrs Drummer, Mond & Co., Limited,
Northwich.
Referring to the common practice of COM
pairing gas engines with those working by
steam, Mr.. ROlason pointed out that diff
ferent set of conditions exists. He ex-
planned that gas engine is machine which
has to automatically control the amount
Of combustible matter required to be ad-
mitted to it's cylinder in proportion to the
work given out by its crank shaft, how
ever variable that work may be, in order
to keep the speed constant. Excepting the
fy-wheel, there Is no reserve Of power be-
hind the piston. as in the steam engine.
But If a practically constant gas is used,
however low Its calorific power may be. the
engine can be so adjusted as to give the
best results This was shown by another
table and diagrams from the report Of the
| gas engine research committee.