twenty-four hours, since the accumulated warmth is counted only once, while the freshness, partaking of the night, is repeated twice. It would come nearer the truth to assume the middle point between the maximum and minimum, though even this cannot be deemed absolutely correct, because the heat neither mounts nor declines in an uniform progression. The hottest time of the day is generally about two o'clock in the afternoon, and the coldest just before sunrise. The hour of extreme descent is consequently, in most latitudes, very variable; and it would be difficult to fix the times suited for observing, unless they were more multiplied. But even fewer observations could sometimes be made to serve the purpose. In this climate, the daily average heat may be reckoned from that of eight o'clock of the morning; and the month of October is found to have nearly the mean temperature of the whole year. The observations usually made with the hygroscopes of Deluc or Saussure, cannot be regarded as affording any definite indication of the dryness of the atmosphere. It would essentially contribute to the advancement of meteorological science, if the hygrometer, which I have described, were introduced into general practice. This adoption cannot be very distant *. Some of the monks, in the religious houses dispersed over the Continent, might find agreeable and useful occupation in recording the state of the atmosphere. Many of these establishments are seated in lofty and romantic situations; and several of them, destined by their founders for the charitable accommodation of travellers, occupy the summits of the most elevated and inaccessible mountains. Accurate registers kept in such towering spots would be peculiarly interesting. Meteorological registers might be regularly kept by the junior surgeons in all our medical depots which are scattered over various points of the globe. Lighthouses, too, would, from their usual position, be well fitted for observing the force and direction of the wind, and the swell and relapse of the tide. The elevation of the water could be most accurately noted by extending a leaden-pipe from the shore into the sea, and bending the nearer • We purpose soon to give the results of some interesting observations made with this instrument in the West Indies, and in New South Wales. end of it into a low cellar where a vertical glass syphon is attached to it. Our navigators who traverse the ocean in every latitude, besides keeping meteorological journals and taking soundings, might record the variation of the needle, and examine the intensity of magnetic attraction. To promote the science of meteorology, it would be most expedient that the various learned associations, planted in different parts of the globe, should institute inquiries into the state and internal motions of the higher strata of the atmosphere. As the ultimate results would prove advantageous to the public, the several governments, both in Europe and in America, might be expected to defray the moderate expence of carrying this plan into effect. Light small balloons could at times be launched towards the most elevated regions, to detect, by their flight, the existence and direction of currents which now escape our observation. Barometers, thermometers, hygrometers, and perhaps æthrioscopes, in compact forms, and which should register themselves, might be sent up in the car. Observers, furnished with accurate and complete instruments, could likewise be dispatched occasionally to the intermediate heights in large balloons. By classing the various meteorological journals, and combining those ulterior facts, some new lights could not fail to be struck out, which would gradually reveal that simple harmony, which assuredly pervades all the apparent complication of this Universal Frame. The chief instruments here mentioned, and of the best and most accurate construction, may be purchased of Mr John Cary, optician, London, and of Mr Adie in Edinburgh. Prices according to the style of mounting, N. B.-Mr Cary manufactures the staff-thermometers Adie, Rutherford's thermometers. OCTOBER-DECEMBER 1826. Description of the Eruption of Long Lake and Mud Lake, în Vermont, and of the desolation effected by the rush of the waters through Barton River, and the lower country, towards Lake Memphremagog, in the summer of 1810, in a Letter to Prof. Silliman *. By the Rev. S. EDWARDS DWIGHT. With a Plan of the Lakes. (Plate III.) MY DEAR SIR, Boston, April 4. 1826. I LEFT Burlington on Monday, August 18. 1823, and proceeded on horseback, in company with Mr an alumnus of Burlington College, to Craftsbury, sixty miles; where we arrived at 2 P. M. on Tuesday. Through the kindness of my fellow traveller, an inhabitant of Craftsbury, I was able to engage a select and very agreeable party of five gentlemen to accompany me, on the succeeding day, to the bed of Long Lake, in the town of Glover,—the lake which was emptied of its waters in the summer of 1810. In the course of the afternoon, I had leisure to examine the local situation of Craftsbury. This village is built on a table-land, rising abruptly in the centre of a deep valley, which surrounds it on all sides, and separates it, at a moderate distance, from hills generally of the same height with itself, but occasionally aspiring to a greater elevation. This table-land is about three miles in length, and one and a half in breadth. The valley surrounding it was once probably a lake, and the table-land a large island in its centre. At present it is almost an island; one river winding more than half round it, in its progress through the valley, and a second nearly completing that part of the circuit which the first had left. Its situation is more than commonly beautiful and picturesque; and, in connection with other more solid advantages, bids fair to render it one of the most pleasant and flourishing villages in the state. The population planted here is of a superior character; and it gratified me to learn that the village reading-room, or athenæum, was regularly furnished with the most important reviews and magazines of England and the United States, as well as with * From Silliman's American Journal of Science and Arts, June 1826. |
