perature of the outside air; for, after the heaters have been lighted, the thermometers within the orchard can record only the temperature maintained by the heaters, not the temperature of the air outside. By frequently reading the thermometers outside and noting the rapidity and amount of fluctuation of the temperature, the task of regulating the heaters will be made far easier.

The method is illustrated in the following brief diary of heating operations in Church's Orchard when the lowest temperature of the fruit season occurred:

Friday-Saturday, May 5-6--Maximum 52° F.

3:55 a. m.-Temperature 12 feet above ground, 29.5° F.

If this diary is read between the lines, it will be seen that a desperate struggle was carried on through the night. At 3:55 a. m. the orchard "looked sick" from the intensity of the cold, and a reading was made high up in the trees to see if by any possibility the temperature there was above the perilous 28° F., that was already present among the lower branches. Furthermore, the heat from the oil seemed to rise straight upwards and to become dissipated by rapid radiation. The cloud of smoke, though apparently heavy, was not sufficient to confine the heat.

As a last resource, the pans were opened wide, but with the additional heat the oil began to boil over, and soon there were three incipient conflagrations in as many places to be smothered at once.

However, at 4:30 a. m. the temperature in the orchard had risen to 28.5° F. despite the fact that the outside temperature was still steadily falling. At 5:40 a. m. the temperature both in orchard and the open was rapidly rising and the crisis was past.

The diary of the next night records a struggle more nearly on equal terms and one in which success was assured from the beginning: Saturday-Sunday, May 6-7-Maximum 61.5° F.

The danger was now clearly past, for even the outside temperature was above the degree of injury. The fires in the heaters were allowed to die out gradually. The minimum temperature during the night was 29° F. The temperature of the orchard was maintained as nearly as possible at 32° F. The amount of heating was, therefore, only three degrees.

In all succeeding experiments fuel oil No. 22 was substituted for No. 28 on the assumption that it contained more asphaltum or

soot than the latter and would, therefore, produce a denser smudge, and for this reason one more capable of reducing the radiation on the one hand and of holding in the heat from the oil on the other. And even if the lower grade of oil should produce less heat per gallon, the ability of the soot to confine the heat produced must make it far more efficient even gallon for gallon than the oil of higher grade already used.

The following entry in the diary shows the immediate success of the change:

Monday-Tuesday, May 8-9-Maximum 59° F.

Heating begun. Fuel oil No. 22 used instead of No. 28.

Response to increase in draft on

Difference is four degrees.

heaters is now almost immediate.

Can not get sufficient oil from tank to renew supply in heaters.

The deficiency in fuel, which naturally caused the heat in the orchard to diminish, was finally overcome by drawing oil from the bung instead of from the faucet, which was clogged by the coarse elements in the oil. The minimum temperature outside of the orchard did not fall below 30° F.

The next step was the delicate regulation of the heat in the orchard with the view of saving fuel by maintaining the temperature. within the orchard at only two degrees above the danger point. This experiment also succeeded, thanks to the character of the oil and the sliding cover of the heater.

The following entry gives the series of measurements within the orchard and without. At this time the fruit was setting and consequently the point of danger was 30° F., one degree higher than the danger point for blossoms:

Wednesday-Thursday, May 24-25-Maximum 57.4° F.

Fuel burning low; fires brightened a trifle by slightly replenish

ing the oil.

are:

5:35 a. m..

5:45 a. m..

Fires put out.

In orchard 33° F.

. In orchard 33.5° F.

THE ESTIMATED COST OF ORCHARD HEATING

The essential items in any estimate of the cost of orchard heating (1) meteorological instruments, such as a thermograph and shelter, and at least one standard thermometer to record the temperature outside of the area of heating; (2) fuel oil; (3) heaters and lighters; (4) tanks; and (5) labor. To these may be added a barograph; or, if desirable, certain substitutions may be made, such as a pair of maximum and minimum thermometers in place of the thermograph, and wood or coal in place of fuel oil.

Meteorological Instruments

The meteorological instruments referred to can be obtained in the United States at the prices given below. With the self-recording instruments are supplied pen, ink, and a supply of record sheets.

Standard Thermometer, Green Pattern,
Maximum Thermometer, Green Pattern,
Minimum Thermometer, Green Pattern,

2.75

4.50

3.75

The above may be obtained of Henry J. Green, 1191 Bedford

The above may be obtained of the American agent, Ernest du Vivier, 30 Chambers Street, New York.

Draper Thermograph, small size,

Draper Thermograph, large size,

30.00 $20.00

Furnished by the Draper Mfg. Co., 152 Front Street, New York.

Thermometer Shelter, Mount Rose Pattern, complete, f. o. b., Reno..
Thermometer Shelter, U. S. Weather Bureau Pattern, complete,

f. o. b., Reno,

$15.00

15.00

Automatic Frost Alarms

....

1.50

27.00

45.00

National Electrical Supply Co., Washington, D. C., Thermostat No. 1673, without connections, "Tycos" Frost Alarm Thermometer (mercurial), Single System, "Tycos" Frost Alarm Thermometer (mercurial), Double System, Furnished by the Taylor Instrument Companies, Rochester, New York, or by The Frost Prevention Co., San Francisco.

....

The thermostat is sold without batteries and electric bell; the "Tycos" system includes both. Wire, however, is extra, but inexpensive, insulated electric wire costing approximately one-half cent a foot and plain galvanized wire much less.

Neither of these frost alarms can be recommended unreservedly. The former has been given a superficial test and found apparently reliable within two degrees. The latter is highly recommended by the Hamilton Orchard Heater Company.

Fuels

The quotations of the oil companies at Reno' on fuel oil No. 22 vary according to the amount sold and the point of delivery:

Fuel oil, in carload lots of 12,000-13,000 gals., f. o. b. Reno, is quoted at 32-4 cents.

Oil in drums, holding 110 gals., f. o. b. Reno, 42-6 cents.

Oil in cans or drums, delivered in Reno: Cans containing 5 gals. at 51⁄2-10 cents; drums containing 110 gals. at 414-6 cents.

Oil in tank-wagon lots, delivered in Truckee Meadows, beyond city limits: Within three miles, 42-44 cents; beyond three miles, 5 cents. Oil in bulk at yard, especially for orchardists who do their own hauling, 3-4 cents.

One of the oil companies has offered the loan of a tank wagon for ranchers who prefer to haul their oil. However, the wagon must be returned immediately.

The maximum estimate of expense for oil, therefore, is for orchards near Reno from ten to twelve and one-half cents per tree for each heating. For other orchards this expense must be somewhat greater according to the additional outlay for rail and wagon. transportation. In case the spring is favorable and only two heatings are required, the cost should not exceed twenty-five cents per tree, and would probably be much less, if the unused oil could be stored or returned. However, if the frosts are abnormally frequent, the expense will be proportionately greater. But unless the situation is far worse than it was the past season, the expense for oil should in no case exceed $1.00 per tree at the utmost.

Since no tests of wood or coal have been made, aggregate costs can not be given. Slabs sawed 12 inches long can be procured f. o. b. 1. C. O. D. Fuel Company; Ridenour Fuel Company.