ERRORS OF OBSERVATION. 



427 



degree of velocity and terminates at the utmost degree of tardity in the middle of the 

 arc. The remission {dy : dw negative) begins from the same middle point with the 

 utmost degree of tardity, and terminates with the highest degree of velocity. But lest any 

 body should babble about this, utmost velocity is understood in respect of any other which 

 is not of the same kind of figure, for it is not denied that one semicircle begins with a 

 greater velocity than another. By how much greater the semicircle, by so much greater 

 the initial velocity* and the final tardity. Here is a clear idea of fluxional velocity, and 

 even of infinites and zeros in other ratios than that of equality. Probably more infor- 

 mation may be found in two manuscript works of Oresmius mentioned as existing by 

 Fabricius (Bibl. Lat.) with the titles De uniformitate et difformitate intentionum and De 

 proportione velocitatum in motibus. I give this account as tending to shew that the 

 fluxional principle is not the comparatively recent introduction of one mind, but the 

 common property of an old and wide school of thinkers, 



March 17, 1862. 



• In quolibet circulo incipit intensio latitudinis a summo 

 gradu velocitatis : et terminatur ad summum gradum latitudi- 

 nis tarditatis scilicet in medio puncto arcus. Remissio vero 

 que incipit ab eodem medio incipit a summo gradu tarditatis 

 et terminatur ad summum gradum velocitatis patet in figura 

 c. d. Verumtamen ne possit aliquis garrulare intelligo sumraam 

 velocitatem respectu alicujus alterius quod non est talis figure : 



non enim nego quin unus semicirculus incipiat a majori reloci- 

 tate quam alius, nam quanto semicirculus est major tanto 

 incipit a majori velocitate intensio latitudinis sue et terminatur 

 ad majorem tarditatem et e converso de remissione. (From the 

 reprint in Tannstetter's collection of five tracts, Vienne, 1515 ; 

 the quotation begins on the verso of h iii.) 



