On JVinds. 313 



■niiles per in'mute, if it had not been that before the air at 

 the tropics could arrive at the equator, it muft have gained 

 fome motion eailwards from the i'urface of the earth or fea, 

 whereby the relative motion is diminiflied to the degree that 

 atSluaily exiUs in it. 



This' theory appears to me rather Ingenious than folid, for 

 the following rcafons : 



1. The trade winds are commonly gentle, moving only 

 at the rate of eight miles an hour ; therefore they have fuffi- 

 cient time to gain or participate of the motion of the earth; 

 therefore their contrary courfe muft arifc from an abfolute 

 caufe, and cannot be deemed merely relative. 



2. Becaufe the north-eaft wind fcarce ever approaches 

 nearer than eight or ten degrees to the equator, and there 

 dies away ; Vv-hereas it ought there, according to this theory, 

 to be ftronireft. And, on the contrary, the fouth-eaft pafles 

 the equator feveral degrees, even when the fun is in the I'outh 

 tropic. A fitft which, as Gentil remarks, is abfoluteiy irre- 

 concileable with this theory. (Gentil Voy. i. p. 6^,'^ ; Ibid. v. 

 p. 116.) 



3. Becaufe, if the conftant eafierly wind was m the north- 

 ern hemifphere fupplied folely from the north, and in the 

 fouthern hemifphere folely from the fouth, we fbould in the 

 former have a conftant north wind at leaft at 35 or 40 degrees 

 from the equator, or at leaft from fome northern point, and 

 in the latter a conftant fouth wind, or at leaft from fome 

 fouthern point; whereas, on the contrary, a fouth wind 

 often prevails in thofe latitudes on the north lide of the equa- 

 tor, and a north wind on the fouth fide. Thus La Pcroufe 

 met an E. S.E. in north latitude 32°, and a due eaft in lati- 

 tude 31''; and a S.S.E. in latitude 14°, and a due eaft in 

 latitude 16 ; and a due north in latitude 20°, (where then 

 was the relative motion?) and a due fouth in latitude 33'^. 

 (See his .Journal in La Peyr. Voy. iii.) He alfo met with a 

 due north in latitude 27' and 42"' fouth, and a N. N. E. in 

 latitude 25'' fouth. So captain Cook met a S. S. E. wind in 

 latitude 30^ north, and alfo in latitudes 40- and 41°, and a 

 idue foutU wind in latitude 38° and 20'; and in the I'outhern 

 hemifphere a due north in latitude 3", 4°, and 44°. I might 

 produce other inltances from fea journals, anil particulaily 

 from that, moft ample and inftrudive, kept i)y major i)ai- 

 rymple during a vovagt to the Eaft Indies (Phil. Tranl. 177^); 

 but I think the alleiied fufticiently prove tii it the general call 

 wind is not fupplied folely from tlie north or loulh ui the dif- 

 ferent hemifpheres rcfijec-tivc'ly. 



4. Becaufe, during our fix i'ummer months, when the fun 

 »s in or approathfjs lo the norihcrn tropic, ihc eafierly trade 



wind 



