cumulo-stratus, to the cirro-stratus and cirro-cumulus; the latter positively charged, and considerably retentive of its charge; the former less perfectly insulated, and, perhaps, conducting horizontally; we arrive thus at the region, where the cirrus, light, elevated, and extended, obeys every impulse or invitation of that fluid, which, while it finds a conducter, ever operates in silence; but which, embodied and insulated in a denser collection of watery atoms, sooner or later bursts its barrier, leaps down in lightning, and glides through the nimbus from its elevated station to the Earth. Thunder storms on the 19th. Weather on the 18th, The first storm cribed. Interval. VIII. Account of the Thunderstorms on the 19th of August. In a letter from THOMAS FORSTER, Esq. SIR, To WM. NICHOLSON, Esq. I The 18th was warm, the maximum of the thermometer being about 73°. Cumuli prevailed during the day, but towards evening the cirrus appeared. Betore 3 o'clock in the morning of the 19th, the sky was clouded. I observed two strata; the upper one appeared to be a uniform veil of cloud, while loose flocky cumuli floated beneath it; and in some places large masses seemed to be attracted towards it, and adhered to its surface, forming an unusual wavy sky, which increased in density. About half after eight I heard a single explosion, like the report of a large brass cannon; about twenty minutes after which two more such reports were heard, following each other in rapid saccession, which were immediately succeeded by a long and loud peal of rolling thunder. The storm now came up yery fast, in a direction nearly contrary to that of the current of wind below, with hard rain, and thunder and lightning. After the storm had subsided, cumuli were again seen sailing under lar kinds of under a continuous sheet of cloud; some of them were loose flocculi, others large well defined masses. By degrees they became lost in the upper stratum; the sky became again Second stofifi: very black, and thunder and lightning with rain again prevailed. During the process of the storm I heard, (beside the many peals of rolling thunder) another loud single explosion, which sounded like the Hollow report of a mortar ; it was preceded by a very vivid flash of lightning. I dwell Two dissimil.. particularly on this circumstance, because I have often no- thunder: ticed during storms two very dissimilar kinds of thunder. One is a long roll increasing in loudness while it continues; this is supposed by Mr. B. P. Van Mons to be caused by combustion of the two gasses of water: The other is a loud and sharp explosion of short duration; and often a single report like that of a cannon; the lightning which precedes this is generally vivid and mischievous, it darts di rectly towards the Earth, or any other prominent object, as high trees, towers, &c., and is considered by Mr. B. P. Van Mons, as the flying off of electricity from an overcharged cloudt. I wish to direct the attention of meteorologists to the solution of this question. When mischief is done by lightning, is not the thunder which follows the flash generally of this latter kind? The variations in the direction of the wind below, in Various cufstormy weather, as well as the contrary directionis of the stormy wea current above, constitute another curious object of philo- ther. sophical speculation. Small air balloons might, in this Small air bal case, become useful meteorological instruments. I have loons as a mëteorological sent up a great many of them, and have generally seen then instrument moved by several different currents of air. Clapton, Hackney, 22d Aug. 1811. Yours &c. THOMAS FORSTER: • See Journal for October, 1809, Vol. XXIV, p. 106. The distinction of rain, into "rain of the decomposition," and “rain of the recomposition" of air, by Mr. Van Mons, has induced me to inquire, What is the electric state of rain with a rising, and what with a falling barometer! NOTES N. B. The observations in each line of the Table apply to a period of twentyfour hours, beginning at 9 A. M. on the day indicated in the first column. A dash denotes, that the result is included in the next following observation. set NOTES. 20, 21. Forty-eight hours rain. July 15. Small rain about 2 p m. 19. A thunder shower early: fine day. 22. Temperature 60°, (the maximum of the period) at 8 a. m. 26. Orange-coloured cirri at sun27. Thunder clouds: a few drops p. m.: much dew. 28. Cirros cumulus cloud, very beautiful, interchanging with cirrostratus, succeeded by large cumuli. In the evening some appearance of a thunder storm far in the N. W. 29. Evening parallel bars of cirrostratus, stretching E. and W.: a blush on the twilight. 30. Windy, cloudy. Aug. 2. Large elevated cirri. 3. Cirrocumulus, followed by cirrostratus: evening overcast: rain by night. 4. Windy, at S. W. by night. Cumu lostrati, in various quarters, at sunset. 7. Opaque twilight, with cu mulostratus. 8. Very wet, a. m.; at noon a thunder shower; at 6 p. m. a heavy squall from N.W. with rain and hail; the nimbus, as it receded, presenting a perfect and brilliant bow: windy night. 9. Large cumuli rose, and at noon inosculated with the clouds in a superior stratum: a thunder shower ensued before 2 p. m., after which appeared the distinct strata again: about 6 p. m. a second thunder shower, long very dense in the S. E., where the bow was conspicuous above an hour. This day was nearly calm. 10. Rain fell again about noon, upon the union of two strata of cloud. RESULTS. Prevailing winds, westerly. Barometer: max. 30:15; min. 29:35. Mean 29·835 In I have the satisfaction to acquaint my readers, that the Meteorological Tables and Remarks, which will hereafter appear in this Journal, will be extracted (as the present has been,) from the journals of Mr. Luke Howard, whose Treatise on Clouds, inserted in the present number, and long known and valued by the public, will make it unnecessary for me to express, in any direct terms, that sentiment of obligation, which myself, and the other cultivators of scie ence, must entertain for his researches. W. N. VOL. XXX. SEPT. 1811. X. Mode of analysing vegetable and animal substances. Difficulties. Methods of obviating them. Abstract of a Memoir on the Analysis of Vegetable and Animal WHEN we conceived the design of studying the ana lysis of animal and vegetable substances, the first idea that occurred to us was, to convert, by means of oxigen, vegetable and animal substances into water, carbonic acid, and nitrogen: and on this we fixed our attention. It was evident, that, if we could effect this conversion so as to collect all the gasses, this analysis would attain very great accuracy and simplicity. Two obstacles appeared in the way of this: first, the burning of the hidrogen and carbon of these substances completely; and, secondly, the effecting of this combustion in close vessels. The first we could hope to surmount only by means of metallic oxides, that easily part with their oxigen, or of the hyperoximuriate of potash. A few trials soon led us to prefer this salt, which succeeded beyond our expectations. It was far from being so easy to surmount the second: for we could not attempt the combustion in a retort filled with mercury; since the retort would have burst, had we burned ever so little in this way. It was necessary therefore to conApparatus re- trive an apparatus, in which we could quisite. Description of answering 1st, Burn parts of a substance so small, that the vessels should not crack: 2dly, Effect such a number of combustions successively, that the results should be very perceptible: and 3dly, Collect the gasses as they were formed. An apparatus of this kind we lay before the class. It is an apparatus formed of three separate pieces. One is a tube of very thick these purposes. glass, hermetically sealed at the lower end, and open at the upper; about 2 dec. [7.87 in.] long, and 8 mil. [3.15 lines] in diameter. This has a very small tube, likewise of glass, similar to what would be adapted to a retort to receive gasses, joined laterally to it by means of the blowpipe 5 cent. * Ann. de Chim. Vol. LXXIV, p. 47. Read to the Institute the 15th of January, 1810. [1.97 in.] |