168 IVr'ight &c. on an Universal Measure; 



the mcisures observed by all those different nations, who 

 traffic together, are reduced to that which is commonly 

 known and received by anv one of them ; which labour 

 would be much abbreviated if they were all of them fixed 

 to any one certain standard ; to which purpose, it were most 

 desirable to find out some natural standard, or universal 

 vicasnre, uhich hath been esteemed by learned men as one 

 of the dcsidtrata in philosophy. If this could be done in 

 longitude, the other measures might be easily fixed from 

 thence. 



" This was heretofore aimed at and endeavoured after in 

 all those various measures derived from natural things, 

 though none of them do sufficiently answer this end. As 

 for that of a barley-corn, which is made the common 

 ground and original of the rest, the magnitude and weight 

 of it may be so various in several times and places, as will 

 render it incapable of serving for this purpose ; which is 

 true likewise of those other meajiures, an inch, palm, span, 

 cubit, fathom, a foot, pace &c. ; none of which can be de- 

 termined to any sufficient certainty. 



" Some have conceived that this might be better done 

 by subdividing a degree upon the earth ; but there would 

 be so much difficultv and uncertainty in this way as would 

 render it unpracticable. Others have thought it might be 

 derived from the quicksilver experiment ; but the unequal 

 gravity and thickness of the atmosphere, together with the 

 various tempers of air in several places and (seasons, would 

 expose that also to much uncertainty*. 



" The most probable wav for the effecting of this, is that 

 which was first suggested b)' Dr. Christopher IVrun, namely, 

 by vibration of a pendulum ; time itself being a natural 

 measure, depending upon a revolution of the heaven or the 

 earth,^ which is supposed to be every where equal and uni- 

 form. If any way could be found out to make longitude f 

 commensurable to time, this might be the foundation of 2^ 

 natural standard ; in order to which, 



" Let there be a soHd ball, exactly round, of some of the 

 heaviest metals ; let there be a string to hang it upon, the 



* §jnce Biihop IVUkim wrote the above, Hullfy, ConJaniine, Gccii?i, 

 and others, have ascertained that, at and nenr the equator, there is htile 

 or no ''ari.ition in the height of the b.irometer, except ciui ing hurricanes. 

 See Phiios, Trans. No, iio; and Ttmjdeniani Extracts from the Mem. 

 (ie I'Ataii. R. dn .V . p. 3 la, 



+ The IcHrned author, by longitude means length; for longitude, 

 ulien it bignifies an arch of rht- ecpiator, between the first meridian and 

 any other, may be said (loosely not ni^itliematically) to be commensura- 

 ble 10 time J sini.e 13 degrees of longitude answer to an hou'', &c. 



emallest, 



