32S Progress of AJlrondmy in 1S05, hi/ Lalande. [Nov. 1, 



extraordinary hurricanes which are fortu- 

 nately rare in Europe, which root up 

 trees and unroot" houfcs. Heretofore it 

 appeared to me to be abiioll impudible 

 to dii'cover tlic caiifo of them ; but my 

 journey to Lyons furnilhed me witli an 

 idea which may probably be correct. JM. 

 Molet, an able profefforof natural philo- 

 fophy, found in his notes that there was 

 thunder on tlie above-mentioned day at 

 l/vons. As I palied throujrh Sens I faw 

 M. Soulas, who informed >ii)e that the 

 wind had chanifcd from "north to fouth.''^ 

 From the public journals I learn that a 

 violent llorm happened the fame day, at 

 London. Here was iheii,- as I conceive, 

 a mafs of elettrical clouds, one hundred 

 myriametres in extent, wLofc detonation 

 produced a,n invmenfc vacuum, that 

 might have obliged the air to ru(h ahnvx 

 with violence to till up tlus vacuum. Of 

 this I had a confirmation on the 11th of 

 January, 1306. Extraordinary thunder 

 at Breft, Rouen, Cliartres,-^nd Ypresj 

 produced tenioells and hurricanes which 

 demolilhed chimnies at Bourdcanx, Be- 

 fanfon, Nancy, and Dijon. \'ioIent 

 ' claps of thunder arc rare at that fcafon ; 

 but the fou;h wind had pccafioned heat ; 

 the air was rainy, tlie clouds low, and ca- 

 pable of drawing fparks from the earth 

 over a fpace of fixty myriametres. There 

 were even fome fymptoms of earth- 

 quake. \ 



The hurricanes of the lile of France 

 and of America, which are rar.ch more 

 violent, would juftify the fuppoUtion of 

 ftormy malVes of far greater e.ttcnt ; to 

 which niLty likewife be added water- 

 fpouts and fub-marine eruptions. 



M. Fiot, Infpettor-Geiitral of Salu- 

 brity, has fent me the refult of the 

 lieights of the river obfervcd daily during 

 the year 13. The mean Rate of the ri- 

 ver fur this year is 1.3.5 on tlie llandard 

 of the bridge of La^Tourmlle, inftead of 

 .1.24, as Ifnmd the average of eighteen 

 yearsj^from 177/" to 1794 ; therefore the 

 year 13 has been conlideied as a rainy 

 year. Some years, however, it has been 

 1.73, as in 1737 ; but in others, on the 

 contrary, only 0.59, ns in 1803. 



This height, is relative to the low waters 

 1719 ; but the river has lometimes been 

 lower Ijy fcvcrai centimetres. 



The Academy of Turin has ])ubli(hcd 

 its Memoirs for 1804 and 180.5, in which 

 tiiere is a new barometer by M. ValTah 

 Eandi, with altitudes meafuscd in Pied- 

 mont. 



M. Beraud_, who for thirty years has 

 xnade an iiuinenfc nuir.l.er of uactcorolo- 



gtcal obfervations in Piedmont, and who 

 Hill ci)!itiai:ss to do fo, notwitliftandinf^ 

 his a.lv;mce>! age, has lent us thofe for 

 the year 1805. 



Meteorology and navigation can alike 

 lay claim to aJVIemoir by M. Biot, who, 

 by means of an internal loadltone, ac- 

 counts for all the declinations and incli- 

 nations of the ncedje, bbferved by M. 

 Humboldt during his voyages and tra-. 

 vels. 



An extraft from an nnpubliflicd Me- 

 moir by Tobia^ Mayer has been tranf* 

 niitted to me by his fon. It contains an 

 hypothcfis for explaining the inclinations 

 and declinations obfervcd. He fuppofes 

 that, in the interior of the earth, tiiere is 

 a very fmall load (lone with two poles, 

 the centre of which is one-feventh of the 

 r.adius difiant from the earth, and re- 

 moves from it annuylly'-j-Jog. • 



M. Azimi has pub'ilhcd a Dilfertation 

 on the Origin of the IvIariiier's'Compafs, 

 to prove that the French were the Hrft 

 that made ufcofjt. .It was known in 

 France in the 12th century by the name 

 of marin'ure, and .\vas, employed during 

 the reign of .St. Louis. Gioia of Amalti, 

 to whom the invention is afcribed, did 

 not live till about the .^-car 1300. The 

 flower-de-luce has beenemployed in the 

 compalfes of every country. I had al- 

 ready remarked, in my Abridgement of 

 Navigation, that Father Xiinenes, a cele- 

 brated Italian aftror.omer, Ivad proved 

 the priority' of the French. 



Melfrs. Arnold and Eariifliaw, Englifli 

 watchmakei's,' on the 7tii of June, '18U4, 

 prefented to the Boaid of Ix)iigitude at 

 London their efcapcmcnts for time- 

 keeper.*, chronometers, or marinc- 

 v.atchcs, and they liave boon made pub- 

 lic by the Board. That invented by .M. 

 Brequet at Paris is defcribed in the vo- 

 lume of -the Uifiory of Mathematics by 

 Moutucla, ill which I have given the Hif- 

 tory of Machines. 

 , Nautical afironomy has been enriched 

 with ail important work intitlcd A Com- 

 plbte Collection of Tables for Naviga- 

 tion, by M.de Mendijza, aSpaiiifli ollicer 

 long rohdcnt in England. It forms a 

 quiirto volume of 727 pages, and com- 

 prizes all the tables necelfary for cor- 

 recting altitudes and dillances by the 

 moll timple nicthod that has yet been 

 difc(j\cre.d, being reduced to the addition 

 of tiiree numbers which arc found in 

 thefe tables. It further comprehends 

 the logarithms, the femi-diiirnal arcs, the 

 am>)litudes, a very ample Table of the 

 lonj^itudes and latitudes of dilTerpnt 

 places. 



