277 



mense difference shews that by the junction of 

 the springs, by feeding-trenches, and well-es- 

 tablished reservoirs, an able engineer might 

 avail himself in central America, of circum- 

 stances which are wholly dependent upon the 



inches; at St. Domingo 113 inches. {Arago Annuaire du 

 Bur. des Long., 1824, p. 165.) M. Antonio-Bernardino Pe~ 

 reira Lago, colonel of infantry of the corps of engineers, at 

 Brazil, thinks he found, in the year 1821 only, at San Luis 

 do Maranhao, (lat. 2° 29' south), 23 feet 4 inches, 9*7 lines, 

 English measure, which make near 260 French inches. We 

 might be inclined to doubt this prodigious quantity of rain j 

 yet I am in possession of the barometric, thermometric, and 

 ombrometrir observations which M. Pereira Lago affirms 

 were made by him, day by day at those different periods. 

 These Brazilian observations are published in the Annaes 

 das Sciencias das Artes et das Letras, p. 54 — 79 ; and the 

 observer who describes the instruments he employed, says 

 expressly, in the resumo das observacoes meteor ologicas, that 

 the plane on which the rain fell was exactly of the same 

 diameter as the cylinder which contained the scale ; this 

 diameter was only 6 inches (English). I wish this important 

 observation may be verified at Maranhao, and repeated in 

 Other parts of the tropics, where the rains are abundant j 

 for instance, at Rio Negro, Choco, and the Isthmus of Pa- 

 nama. The quantity indicated by M. Pereira Lago, is 

 2~ times greater than what has been observed at the mean 

 term, at the Isle of St. Domingo $ but the quantity of water 

 that falls on the western coast of England also exceeds three 

 times that which is collected annually at Paris. There exists 

 very considerable differences in latitudes, that are near each 

 other. Captain Roussin relates that 151 inches of rain- 

 water fell at Cayenne, in the month of February only. 



