- 402 Correspondence of J. Nicklés. 
>. . ‘ . 
int South Germany into one summer-maximum, when the period 
of temporary rainlessness entirely ceases. This is observed es- 
pecially where the current in the course of the year rises and 
falls considerably, and therefore at places, in a word, near the 
outer limits of the current, sometimes within it, and sometimes 
without it. It is clear that ‘where this is not the fact, the changes 
in the temperate zone must be different. The delay of the cur- 
rent in the annual period is thus clearly accounted for. 
As early as 1675, Seller laid down the inner limits of the 
northeast current in the Atlantic Ocean, very different from Hors- 
burg in the early part of the India Directory. According to him, 
the zone between the two currents is fifty miles broad in winter, 
and one hundred and twenty in summer. Lately, Maury has 
tried in his large atlas, to ascertain the change of the northeast 
current for each month. He has shown clearly that this change 
is greater on the African than on the American side, or as I had 
before inferred, from the barometric phenomena, that the limit of 
calms and the associated phenomena of the current do not move 
in parallel lines but like a swinging thread, having its node-point 
in the West Indian sea, where the trade wind is a constant wind, 
and its greatest breadth of swing in the Indian Ocean, where it 
turns into the monsoon. How these extremes pass in the inte- 
rior of Africa bags one to the other, that is, how the current be- 
comes a monsoon, we do n ot know, since most African travellers 
think that they have quite gee their tribute to meteorology, by 
complaining of the long continued heat there 
(Zo be continued.) 
<= 
Art. XXXVIII.—Correspondence of M. Jerome Nicklés, dated Paris, 
ept. 1, 1855. 
The ether machine $ M. Tre embl ey* is among them. The boiler is 
open to view. It has been rendered perfectly tight, by plunging the 
System of tubes which compose it into melted bronze he ether 
vapor is thus completely confined and escapes only by the atari’ 
openin 
" Boutigny exhibits his small boiler, by which the surface of evapora- 
e. 
M. Franchot has there his hot-air machine, as it was made in 1836. 
The Arithmometer of M. Thomas de Colmar is presented on a large 
scale, adapted to calculate 30 numbers—which is beyond the wants 
* This Journal, Noy., 1858. + Ibid, May, 1853. Ibid.  § Ibid, May, 1855. 
