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rhispurpofehcalledgesapaflragcoutof Abulfeida^ to this cffeft, 
that Almamorj^ a Prince of the Arabes^ defirous to know, what the 
Truemeafureof diCtkiWdX Degree might be upon Earth, com- 
manded the Experiments to be made iij the Plains of Sanjar\ where 
a Station being chofen, and thence Troups of Horfcmen let out, 
that went in a ftraighc line, till one of them had raifed a degree of 
JLatitude^ and the other had deprefl: it ; at the end of both their 
marches, they who raifed ic, counted $6^- miles, and they who de- 
preft it, reckon'd 56 miles )uft. This Obfervation can inftrud us 
but very little, becaufe we know not jiiftly, of what length thefe 
miles were. Then, the Author obferves, that the Ancient com- 
putations of miles for a Degree run alwayes upon the decreafej 
fo as Ariftotle counting to a Degree r r 1 1 fisdia , after him Erato- 
fihenes counted but 700 ; PbJJidonms but 666 ; Ptolomy but 500. 
Nor do thefe Obfervations teach us any thing certain, becaufe the 
precife length of thefej?^^/Ww is unknown to us; and they were 
alfo different among themfelves ; the JladU jilexandria differing 
from thofeof Greece. At lafl Fer;jelm brought it to 56746 Tcifes 
or Fathoms of Paris, each of which is equal to 6 Parijianktt; 
Snellm^ to 5502 
In the fecond Article^ he judges Snellm his way of meafuring to 
be the moft artificial ^ which was by a Scale triangles. But in 
»ne thing he efleems it deficient, v;hichis, that Snelliffs took his 
Objeft only by Pinnules, or Common Sights , which do not fo di- 
ftinftly point it out. 
. In the third Article he begins to fpeak of his own Method, and 
its cxaflnefi, and faith, That, when the refolurion was taken of 
See Fig. I. Meafuring a TDegree^ he chofe his Meridian^ out of which 
Tab. I. he intended to take his Meafure, httv^t^viSourdpn in P/- 
cardy^ and Mahoyjin^ which is upon the confines of the Gajiipois 
and Hurepois, To attain the exaft Meafure of this Arch of the Me- 
ridian, lying betv^een Sfj^^r^t?;^ and Malvoyfif?^ he faith, heafluaMy 
meafur'd a way that lay very ftraight , between ViU ejuifve zi\d /- 
"voify, viz. A. B And be began to meafure from the mixldle of a Mill 
^iViHejmfve.^wd continued till he came to the Pavilion cffo^j/^.and 
found the diftance between thefe two teenies, in going fcrward> to 
be s^'^^ toifes and 5 feet, and in commingback, 5663 tolfes and 
I foot ; which being meafured with greac exaftnefs, he flated the 
diftancc between thefe two places,in round reckoning, 5 663 toifes. 
The 
