quantity passing gradually increases till a second channel opens out, and later on a third one, and so on.

By this means the quantities of oil and steam passing to each burner can, at any moment, be regulated with the greatest nicety, and perfectly adjusted to each other.

There are three burners in position at the door opening, placed along the top of the furnace inclining slightly downward as they enter, and reaching

from four to six inches inside.

Where the old grates, formerly used for burning coal, are replaced by those for burning oil, the latter (see F) are iron plates perforated with quarter inch circular holes.

The floors of the ash-pits are covered with a layer of sand and ashes mixed, for the purpose of absorbing any oil that may not be consumed, of which the amount is minimum.

The flame, a very long one, is at the mouth of the burner intensely hot and dazzling white, and almost smokeless.

The combustion, however, is not perfect, for the force of the blast propels small particles of the heavier oils through the flame to the walls of the furnace, where, if not consumed, they find their way to the ash-pit.

The air admitted through the grate, beneath the burners, is not sufficient for the oil's combustion, but by the following described very ingenious. arrangement, the flame is met by a fresh supply of air and the consumption of the oil is made more nearly complete. A few feet in front of the burners a low, hollow arch of fire-brick runs transversely from side to side across the floor of the furnace, thus occupying a position similar to that of the fire-bridge in an ordinary furnace, but the flame does not pass immediately over the arch. On top of this arch rests the foot of another fire-brick arch, as shown in Figures 1 and 2, which spans the furnace transversely, and at the same time slopes upwards and backwards to within a short distance of the furnace door, where it stops. The inclination of the burners is such that the flame first strikes the floor of the furnace near the wall, as shown in D, Figure 1. It then turns upwards and backwards, doubling upon itself-passing up under the arch B to near the top of the furnace door, where it strikes and heats the curved tube E in which the steam employed to atomize the oil is superheated; then, curving over the top of the arch B, it passes forwards and downwards toward the flues. As the flame passes over the top of the hollow arch-bridge C, it meets another stream of air, which, coming from the interior of the arch-bridge C, and flowing out through numerous holes in the fire-brick forming the upper part of the arch, aids very materially to complete the combustion of the

oils.

The first boiler flues through which the products of combustion pass are large ones, twelve to eighteen inches in diameter, but quite short. Under the central portion of the boiler comes another chamber, where further combustion can take place and more air be supplied if needed.

SOUTHERN PACIFIC COMPANY, OFFICE AUDITOR M. P. & M. DEPT.,
SAN FRANCISCO, February 16, 1886.

Col. C. F. CROCKER, Third Vice-President Southern Pacific Company :

DEAR SIR: Some days since you handed me a statement showing the amount of water evaporated to one pound of Carbon Hill coal under an ordinary stationary boiler; also amount evaporated to one gallon of petroleum on steamer Piedmont.

While it is hardly fair to make comparisons between a stationary boiler and boilers on a steamer, the figures given show very favorably for the Carbon Hill coal; though it would be interesting to know at what temperature the water was furnished the stationary boiler. I have no doubt but that it was furnished at, at least, 150 degrees Fahrenheit, while the water furnished the Piedmont boilers was at about 50 degrees Fahrenheit. This of course would cut a considerable figure in the calculations. We have no stationary boilers that are burning oil, therefore cannot make comparison on that basis; though scientific works on this subject give "the equivalent evaporative power of one pound of combustible under one atmosphere at 212 degrees Fahrenheit," as follows: coal, 14.62; oil, 28.50. I desire to submit the following, which may be of interest to you. From tests made on steamer Piedmont we find the following:

One ton of Carbon Hill coal evaporates ten thousand nine hundred and sixty gallons of water at a cost of $5 40, or $.00049 per gallon.

One ton of oil (two hundred and fifty gallons) evaporates twenty-two thousand six hundred and eighty gallons of water for $10, or $.00044 per gallon, which shows a saving in oil over coal of $.00005. In both cases the water was evaporated from about 50 degrees Fahrenheit.

The figures given below will show the relative cost for running steamer Piedmont with coal and oil.

In months of May, June, July, and August, 1885, when burning Carbon Hill coal, the cost was as follows:

In months of October, November, and December, 1885, and January, 1886, when burning oil, the cost was:

By the use of oil the saving is $429 18 per month, or $5,120 16 per year, which is 1044 per cent.

On steamer Thoroughfare the saving is greater than on steamer Piedmont, and on the steamer Solano about the same.

Yours truly,

N. H. FOSTER, Auditor M. P. & M. Dept.

SOUTHERN PACIFIC COMPANY, OFFICE AUDITOR M. P. & M. DEPT.,
SAN FRANCISCo, October 26, 1887.

A. N. TOWNE, Esq., General Manager Southern Pacific Company:

}

DEAR SIR: Inclosed please find statements showing comparison between coal and oil for steamers Transit, Oakland, Julia, and Piedmont. You will note that the saving in favor of oil for the

PIEDMONT.

For months of December, 1886, and June, 1887, with coal:

For months of August and September, 1887, with oil:

July, 1887, with coal:

SOUTHERN PACIFIC COMPANY, OFFICE AUDITOR M. P. & M. DEPT.,)
SAN FRANCISCO, October 6, 1885.

TIMOTHY HOPKINS, Esq., Treasurer Southern Pacific Company:

DEAR SIR: Replying to your favor of some days since, relative to the use of oil as fuel, I would respectfully submit the following. During the year 1884, steamer Solano consumed: