Nature . e wind, but as these conditions cannotalways be realised, in order to attain great heightson this expedition the paper pilot-balloons alreadytried at Trappes were used. Since these balloonswere only intended to show the direction of thewind, they did not usually carry instruments, andtheir drift and height were determined by simul-taneous angular measurements at the ends of a base-line on thi shore, with the exception of one balloonwhich was observed from the boat. These soundingsof the atmosphere, executed at various places, notablyat Madeira, Teneriffe and Cape Verde Islands, andals
Nature . e wind, but as these conditions cannotalways be realised, in order to attain great heightson this expedition the paper pilot-balloons alreadytried at Trappes were used. Since these balloonswere only intended to show the direction of thewind, they did not usually carry instruments, andtheir drift and height were determined by simul-taneous angular measurements at the ends of a base-line on thi shore, with the exception of one balloonwhich was observed from the boat. These soundingsof the atmosphere, executed at various places, notablyat Madeira, Teneriffe and Cape Verde Islands, andalso over the open sea, gave the following results, towhich are added observations of winds on two tropicalmountains and during one of the kite-flights. In the table on p. 56 the first column indicates theupper limit of the north-east trade, and the secondcolumn the limit of the associated north-west heights being expressed in metres. In the thirdcolumn the figures in parenthesis show the maximum. Fig. 2.—Direction of 1 by the tracks of heights at which the balloons were observed movingin the anti-trade, from south-east, south, or south-west. There follow observations at different heights onthe peaks of Teneriffe and Fogo, the figures after thedirection of the wind being its velocity in metres persecond. There is also noted the drift of the cloudspassing above the peaks. The diagrams (Fig. 2) re-present the direction and speed of the balloons whichwere sent up from Teneriffe on July 9 and from on July 17. The tables and figures show that the winds blow-ing inward the equator have a direction varyingbetween and , these last being usuallyabove the stratum, the thickness of this layerof the trades in the vicinity of Teneriffe being about}ooo metres or 5000 metres. Above it blow , S.,and currents which form the anti-trades, itsthickness being probably very great, though itsdensitv is small. Thus, as was deduced from theobservations of cl
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