Porta, on ths Reflection of Cold &t, 165 



for adding, that the latitude of Paris was not settled seventy 

 }jears aher IVrigbt had ascertained thai of London. For 

 M. Auzout (lo whom, or to Kirch, the invention of the nji- 

 cronieter is ascribed by those who are ignorant of the ante- 

 rior claim of our Gascoigne*), in a letter X.o Louis WV. 

 in 1664, says, '< Mais, Sire, c'est un malhcnr, &c. But, 

 Sire, the misfortune is, that there is not in Paris, nor, as 

 far as I know, m your whole kingdom, an instrument on 

 which I couJ<l depend, in taking the exact heliiht of the 

 polef." Thus, Sir, your ingenious correspondent, the 

 £ev. Mr. 7af>lisX, appears to be perfectly in the right, 

 when he aljedges that, if our neighbours have lately over- 

 taken, for 1 would gladly hojie they have not yet distanced, 

 us iri the race of science, it can only be because they are 

 publicly encouraged and supported in their anduuu* pursuits, 

 and we are ?iol. But of this more, perhaps, on some future 

 occasion. It is high time to come to the immediate ob- 

 ject of this letter. 



The marginal title of this curious passasfc of I fright is, 

 " A moe;t exact way to find the quaulitie of the earth's 

 semidiamcter." — The paragraph itself is as follows : " This 

 angle" (the Dip of the Horizon, owing to the elevation of 

 the observer's eye above the surface of ihe sea) "may other- 

 wise be found, the quantitie of the earth's scmidiameter 

 being first known, wliich is to be done divers waies ^ but 

 they may be all reduced to two heads or kinds, whereof the 

 first requireth the certain measure of some areh of the Me- 

 ridiau to be first given, which is also divers waies to be 

 performed. Jiut the best and pcrfectest way of all others 

 (viz. of exaolly measuring the size of the whole earth) is 

 •to observe so exactly as is possible the Summer soUtitiall 

 Altitude of the Sun at two places, so farr distant asunder, 

 and lying so neer North and South each from other, with 

 so direct and faire a u«y betweene them as coni'eniently 

 anay be chosen. Suppose., for example, Portsmouth ancl 

 tiarwick, or some other place in thefujlhesi parts of Scot- 

 Innd ; for the further these placet; are each I'roiu other, the 

 more perfectly may this .businesse be perft^rmed. Then 

 measure, rnd plat down so truly as i« possible, all the way 

 betwtcne those two place*, with all the turnings and wind- 

 ings, ascents and descents that are therein ; out of which 



• Sec Plii!. Trans. i\r.. 25 tg. ; Suv.rirn, Die/. Uniii. de Mmb. tt 

 Me Pl'n. art. Mui'.mitu. Ihoris's Lx. Tt;b. art. Miaoruur. 

 t Sti Asiion. ill- .11 Di lu Luui' , t. 2. p. 842. td. I. 

 X .Stc out x.tth vol. p. 15. 



La the 



