Washington sentinel. [volume] (Washington [D.C.]) 1853-1855, 1854-08-29
Correspondence ofthe Boston Chronicle.
Description Of the Motive Power Of tn,
Arctic.

4
Arctic.
New YoRK, dug. rs, l854.-I have delayed
giving description of the Arctc's machinery,
ana the application Of the motive power EN-
| ployed, In anticipation of trial trip by this
splendid steamer; but as il is now certain that
she will not leave this port for Boston for
nearly fortnight, will give brief account
in the present letter.
| For several months, series of scientific ex--
periments have been made by the liberality of
Mr.. Il. X. Collins, with what is known as Weth-
ereds Patent the object being of increase
the power of steam without any increased ex-
penditure for fuel. The patentees claim as
new "the combining steam superheated or
surcharged steam for actuating engines, when
| generated, the elasticity and increased and
operated as set forth" The patent intends not
steam simply surcharged with heat, but the
/ use of mixture OF saturated and surcharged
steam ordinary steam being saturated with
water, or of maximum density for the pressure,
and surcharged steam being common steam
surcharged with heat, having less than the
maximum density, and therefore not being
saturated with water. A certain quantity Of
| saturated steam Withdrawn from the boiler, and
heated of contact with the water to very high
temperature, then mixed with certain guam
| tity of saturated steam, and this mixture used
to operate upon the engine, a greater power
can be driven from it, with certain quantity
| of fuel, than could be derived from the use Of
saturated steam alone, produced by the same
quantity of fuel.
The mode of obtaining the mixture is as
follows: From the steam chimney of the boiler,
common steam pipe, furnished with the
| necessary stop valves, conveys externally to
| the boiler the saturated steam to the valve
chest; another similar pipe, valves, &C., from
| the same steam chimney, but starting within
the smoke chimney, allows the passage of satu-
| rated steam down the smoke chimney, through
| the fiues and through the furnaces; passing
| Immediately the burning fuel, and having be-
come highly surcharged in its passage, it is led
out ofthe front of the boiler to the same valve
chest where it unites with the saturated steam
From the valve chest, the mixture passes to
the cylinder of the engine, and operates as a
motive power upon the piston.
Numerous experiments have been made by
B. F. sherwood, esq.,, chief engineer of the
United States navy, and Daniel b. Martin, esq,
engineer-in chief Of the United States navy.
The engine upon which the experiments were
at first tried, was non.condensing one the
diameter of the cylinder of which was l2t
inches; the stroke of the piston IL inches; the
cylinder was double or surrounded with steam
4
diameter and 8 feet long, nearly direct from
he boiler to the cylinder. The boiler had YER
ricai tubes and was working model of the
boilers In the Collins line of steamships
With excellent apparatus and in the most
careful manner, experiments were made with
snmon steam alone; with surcharged steam
alone, and with the mixture of common and
surcharged steam in which the proportions
we're as twenty-five to seventy-fve. From
the result it appeared that using the steam
simply sprcharged, produced, with the same
fuel, an increased effect of sixty FIVE per cent.
above what was derived from the common
| steam alone; while an increased effect of LOG
per cent was derived by the use Of the mixture.
Also the increased effect of the mixture was
70 per cent. over what was obtained from the
surcharged steam alone. These results were
subsequently verified by operating with the tow
boat to which / alluded in former letter.
This boat had one engine, with the cylinder 81
inches diameter and 62 feet stroke of biston.
The steam was cut off in the supply pipe by
hy valve, and cardboard at l., the stroke of
piston from the commencement. There was
one iron boiler with the furnace and direct
fues below, and single return ascending Hues
above. steam chimney surrounded the smoke
| chimney, and the average temperature of the
latter was 600 degrees Fahrenheit The steam
for the mixture was surcharged by taking it
from the steam chimney, leading it down the
inside of the smoke chimney, then through the
upper fues, then returning through the lower
direct fues and through the furnace over the
burning coal to the front of the boiler from
which it was led to the supply pipe, there united
with common steam, then brought by a pipe
| externally to the boiler from the same steam
chimney or conductor.
From a tahla of in Japnorv 10 81
carefully prepared by Mr.. Martin, it appears
that the economical efficiency of the mixture
OF saturated and surcharged steam was about
~ 7-l0 per cent. greater than that of common
steam alone. The experiments made with the
mixture and with the saturated steam were
continued the same number Of hours and min
utes; the total number of double strokes of
piston made per minute was with saturated
steam alone, 10 and $40, with the mixture 20
and lilo; the number of pounds of anthracite
coal consumed per hour, producing saturated
steam, was 666 ITO, producing the mixture
44O BIO. In subsequent experiments, it was
found that in given time, the total number OF
pounds of anthracite coal consumed in one
hour, producing saturated or common steam
was 453 $40, producing the mixture 288 $40.
In these experiments, about the same number
OF double strokes Of engine piston was made
The object Of this trial was to make the same
number of revolutions of the wheels in equal
times, so as to give the boat the same speed
the same distance (56 miles) was run with the
mixture and with the steam alone, so that the
difference tells in the fuel only. But with the
mixture, in order TO keep the pressure suffici-
emily down TO obtain the same speed as with
the steam alone, it was necessary to carry their
fires extremely low, so that at times portions
Of the CRATE bars would be entirely bare. No
difficulty has ever been experienced from the
burning out of the pipes conveying the sur.
charged steam.
The results Of other experiments, exhibited
the decidedly superior heating power Of com.
bined steam over the saturated or ordinary
steam, and snrcbarged or superheated steam
Having therefore, carefully experimental
and observed the most satisfactory results, Mr. |
Collins resolved to introduce this kind of mo. |
tive power into the "Arctic," and this design |
has been accomplished successfully. am not
at liberty, at the present writing, 10 give Won |