I v $o On the. Moons Influence on the Atmojpherc, 



n Ov'cahoned by , reading in the Blbliotheque Britannique 



Arts, loin. xix. p.. 227, Mars 1802), an extract 



memoir of Mr. Luke Howard on a periodical variation 



iiie barometer, apparently due to the influence of the fun 



moon on the atmofphere, extracted from the Philofo- 



-'•agazine. 



The author c'ftablifhes his eonclutions upon a year's ob- 



fervations made in rjt^S at Plaidow in Eilex, about" five miles 



call ol London, and on ten years of fimilar obfervations made 



at London, and recorded in the Traiifa£tions of the Royal 



Society from 1787 to 3 796 ,f 



in order to oe more readily underitooil by fpeaking to the 

 eye, Mr. Howard has given a plate divided into lunar weeks 

 according to the four principal phalcs,of the moon, on which 

 are engraved two curves which reprefent the courfe of the 

 mercury in the barometer. One of. thefe, which is dotted, 

 reprefents the courfe of the barometer as obferved at Plaiflow 

 in 1798; the other is a line indicating the variations of the 

 barometer at London, correfponding to each of the principal 

 plans on a mean often years*. 



M. Begnelin at Berlin, and M. Maret at Dijon, have long 

 fince adopted charts of this kind to reprefent the courfe of 

 the barometer and thermometer. M. M. A. Picfet mentions 

 having drawn out one in 1774, in order to compare the con- 

 temporary movements of the barometer at Geneva and Bor- 

 deaux. /"" j 

 I likewife prepared a large one to obtain a parallel view of 

 courfe of the barometer in two correfponding years of tii-e 

 lunar period of nineteen years, from 1768 to 1797. It were? 

 to be wifhed that the ufe of fuch charts could be univerfally 

 >duced, and that they might be always to be had readv 

 ^aved, fo that there fhould be nothing to do but to trace 

 itie curve upon them, as is now the cafe at London. 



Mr. Howard remarks, and the infpe&ion of his plate de- 

 monftrates it, that at the approach of the new and full moon 

 the barometrical line experiences a depreflion, and, on the 

 eontrary, it is elevated on that of the quarters. The greatelt 

 tiepredion of the year 1798 eorrefponds to about twelve 

 hour-; after the new moon on the 8th of the eleventh (lunar) 

 month, and the greatelt and truly extraordinary elevation 



The ilrft mrt-nf this iiarement ife correal, except the mention of two 



curve? ;md an error. of the prel'sin the original (9* for 98). The litter 



part contains a miftake, which the author mull have committed by writing 



rcory. The line here mentioned ierves merely to connect the 



1 points at which the barometer ftood at the time of each phaiis, and 



to Jhow .tl\e chtfcge of level more diftinftly.— Kdit,. 



: occurred 



