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The advantages to be derived from records of the temperature, can but in small part be realized in the present method. A change seems important. It needs no reflection to be convinced that some hours will give a result much nearer the true mean temperature than others. Though the true mean will probably not be ascertained, yet a near approximation may be found by selecting the proper hours. Which hours these are can be determined only by observations. But so far as I can learn, no attempt has been made till the present; and, so great is the task, it will not be often repeated. At the present time the observations are made at very different hours in our country. The following may be mentioned, viz. 7 A. M. and 2 and 9 P. M. at the University of Cambridge, at Williams, Bowdoin, and Middlebury Colleges ;-the supposed coldest and warmest times of the day at Yale College ;—6 A. M. and 6 P. M. or, sunrise and sunset in many places; 8 A. M. and 1 and 6 P. M. are proposed by the Literary and Philosophical Society of New York, as well as the use of Six's Self-egistering Thermometer. The Royal Society, London, seem to make their observations at 8 A. M and 3 P. M. in five colder months, and at 7 A. M and 3 P. M. in seven warmer months. The hours, 7 A. M. and 2 and 9 P. M. have been more extensively adopted probably than any others. The above variety of hours shows the importance of a change. Although it may be doubtful, whether the same two or three hours would give a mean equally near the true, at all places; there cannot be a doubt, it would be nearer the truth than can be obtained in the present method. Can not meteorologists be uniform in their hours of observing the thermometer ? Either of the three following plans, if they would adopt it, would be preferable to the present. 1. The selection of the same two or three hours, or of sunrise and sunset. The object would not be to obtain nearly the mean temperature, but results, from which a comparison of the temparatures at different places might be made. This plan will not, probably, be adopted, because most observers desire to obtain the mean temperature. 2. The use of the Self-registering thermometer, from whose maxima and minima of temperature a inean near the true would probably be obtained. The ease of making the observations strongly recommends this plan. The liability of this kind of thermometers to need repair, or to be inaccurate, is an objection. 3. The choice of 7 A. M and 2 and 9 P.M. which appear from the following results to give nearly the true mean. On several accounts this seems to be the best plan. To get the mean temperature of the day, I took observations at the beginning of each of the twenty four hours, and, assisted by several members of the College, upon whose accuracy and fidelity I could depend, continued the observations for at least five days in succession. I give you several of the results. The first series commenced with March 25th, 1816; the second April 1st; the third the fourth the fifth July 23d ; Oct. 28th ; [five days; Jan. 23d, 1817; and each continued and the sixth embraces 10 days in Jan. and Feb. 1817. This The series of observations were more numerous in winter, because it was the opinion of several gentlemen that the results in winter must be different from those in the other seasons. opinion was very plausible, because the highest and lowest temperature of the day is at different hours in winter and summer. And the reason why the result so nearly agrees with the others is doubtless this, that in winter the temperature at 9 P. M. is several degrees nearer the mean of 7 A. M. and 2 P. M. than at the other seasons. This has been ascertained by Professors Farrar and Cleaveland, and also at this place. As the highest temperature is sometimes between two and three, and sometimes between one and two, had the highest heen noted, instead of that at the beginning of these hours, the results in the fifth column would have been a little greater, than they are there given. The result of various other hours might be given. Williams College, Dec. 16, 1817. 56 Abstract of meteorological observations, taken at Cambridge for December, 1817 and January 1818. By Professor Farrar. Whole quantity of snow about one foot. On the 20th of December, when the thermometer was 15° at Cambridge, it was down to 5° at Lexington, Kentucky; and on the 21st when it was at 16° at Cambridge, it was within a degree of zero at Lexington. Abstract of Meteorological Observations, taken at Brunswick. By Professor Cleaveland. October, 1817. Mean monthly temp. from three observations each day do. do. do. from maxima of heat and cold 45.18° 42.80 67.50 16.25 29.869 in. 1.440 2.550 20 11 do. do. do. cloudy Directions of the winds in proportional numbers, viz. S. W. 15.—N. W. 11.—W. 6.—N. E. 4.—S. 5.—S. E. 3.—N. 1. The prevailing forms of the clouds have been the cirro-cumuli and cumuli, until near the latter part of the month, when the cirrostratus was predominent.-Thunder on the 12th, and a very little snow on the 28th. November. do. do. Mean monthly temp. from three observations each day do. from maxima of heat and cold 37.17° 35.76 18 Days entirely or chiefly fair do. do. cloudy 12 do. Directions of the winds in proportional numbers, viz. S. W. 14 -N. W. 12-N. E. 9—W. 4—Ñ. 3—S. 3. The Cirro-stratus has been the predominant form of the clouds, often accompanied with the Nimbus or Stratus. ERRATA p. 313, read to organize the militia and put the colony in a state of defence.'-p 317, line 9, for resemblance' read' semblance' line 3, from the bottom, for souls' read 'soul'-p. 323, line 9, for 'name' read 'names'-p. 360, line 32, for corrections' read 'correctness'-p. 379, line 11, for same' read some.' |