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Smoking French Vineyards.
able to assess their pro-rata share upon such inhabitants of the districts as refuse to join, and that these assessments may be collected by the taxgatherer, a provision which it would be easier to introduce and enforce in France, perhaps, than in this country." Fig. 10 is an illustration of the protection of a vineyard, from Lestout.*
Making currents of air. - Since frosts occur still nights, it is sometimes possible to prevent them by keeping the air in motion, thereby mixing the air and preventing any part of it from lying on the plant until it shall have become frost-cold by loss of radiated heat. In small areas, as in choice gardens, it is often feasible to employ a man at night to pass back and forth waving a large
*The Lestout system has been used at Cornell with satisfaction.
fan. A windmill may sometimes be set in motion by water-power or other means.
Heating the air.-It is sometimes possible to directly heat the air by means of large fires, although such practice does not seem to have generally met with encouraging results. In the combined smoke and vapor smudges which have been commended by Hammon (page 112), the heat of the fire may add something to the efficiency of the protection. The strong currents of air which are set up by heavy fires seldom aid in the protection of the plantation. Yet there are cases in which hot fires have saved trees over considerable areas from heavy frosts and even from freezes. One of the best experiences in this direction is reported from Florida by Davies.* In the freeze of February, 1895, he was able to raise the temperature in his grove from 18 degrees to 33 degrees by means of fires. "On the north and west sides of your grove have what are called conflagrations, big fires, that will send billows of heat rolling between and over your tree tops; and all through your groves, at short distances, have small fires to help on the good result." Mr. Davies recommends that orange growers "get ready, and keep ready all the time, for the freeze. Once it has come, there will be no time for gathering Your fuel must be on hand, and
materials for fire.
plenty of it." It
is then necessary to keep the fires burning vigorously until the cold spell has passed. H. R. Ste
*D. O. Davies, "Protecting Orange Groves from Cold," Fla. State Hort. Soc. 1896, 28.
vens, on the same occasion, reports success in saving orange trees from cold by burning rosin, securing both heat and smoke. He makes cones six inches high and six wide of common hardware paper which has received a coat of paint. These cones are filled with cheap rosin and set near the trees. A little of the rosin is pulverized on top, and it is then set on fire from a bit of oiled waste which is dropped on it. Six pounds of rosin burn about an hour.
THE PREDICTION OF FROST.
In considering the means of predicting frost, it is first of all important that the student should obtain a clear idea of the usual or average dates of the opening and closing of the seasons of his locality. Records made by himself upon his own farm from year to year are invaluable. He may derive very much help, also, from the records of meteorological bureaus. A general tabulation of spring and fall seasons (see pages 123 and 124) may be suggestive in this connection: *
"The data for the accompanying tabulation of the killing frosts of the region east of the Rocky Mountains was compiled from the bulletins and annual reports of the United States Weather Bureau. The table is divided into dates for spring and fall, and these in turn into earliest, latest, and average
*Made by Alexander D. MacGillivray, Assistant in Entomology, Cornell University.
dates. By 'earliest' is not meant the first frost in the spring, but the earliest date at which the season has opened, while when applied to the fall it is the first actual occurrence of a frost. By 'latest' is meant the last occurrence of a killing frost in the spring, and in the fall the latest date at which the season has closed. The average date is in most cases the mean of average dates given by the Weather Bureau.
"The states have been grouped into three regions, the states of the coast plain, the states of the Ohio River basin and its adjuncts, and the states of the Missouri River and its adjuncts. The first thought in separating the states into these regions was that they represented distinct faunal regions, and that they probably represented distinct climatal regions. This has been sustained in most part. The most marked cases are eastern New York, or the Hudson Valley, and western New York, the former belonging to the coast states and the latter to the Ohio valley states. There is a difference of eleven days in the spring on earliest dates, twelve days on latest, and two days on average; Pennsylvania, which falls in the same category, in the spring, fifty-four days on earliest, eleven days on latest, and twenty days on average dates. In the other regions. the difference is not so marked, and yet there is some difference in all cases.
"This tabulation is of interest in showing the earliest and latest dates at which the seasons have opened, for some of the data is based on records
Mar. 24 June 19 April 30 Sept. 4 Nov. 2 Sept. 4 New Hampshire. April 19 June 9 May 6 Aug. 7 Oct. 30 Oct. 3 Vermont April 8 June 3 May 10 Aug. 5 Nov. 16
Massachusetts... Mar. 26 May 28 April 20 Aug. 8 Nov. 23
North Carolina.. Jan. 3 May 24 April 5
South Carolina.. Jan.
Dec. 29 Oct. 15 4 May 8 Feb. 23 Oct. 15 Dec. 15 Oct. 25 Feb. 2 April 16 Dec. 7 April 7 Dec. 27 April 25 Mississippi. Jan. 16 April 10 Louisiana..... Jan. 12 Mar. 31 Dec. 16 April 13
Mar. 16 Oct. 7 Dec. 10 Nov. 8
Oct. 31 Feb. 6
Feb. 23 Oct. 8 Dec. 27 Oct. 30
Sept. 21 Dec. 29 Dec. 7
Sept. 12 Dec. 27 Oct. 17