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7'2<3 PHILOSOPHICAL TRANSACTIONS. [aNNO 1780. 



From every information, domestic or foreign, and comparing the several 

 opinions, experience and observation plainly and completely determine the dis- 

 pute. The disease among the horned cattle, so fatal in many countries, is not 

 endemial or natural to Europe, though it is become so in Denmark, from spread- 

 ing all over the Danish dominions, and its long continuance in that kingdom. 

 It is an eruptive fever of the variolous kind ; and though the exanthemata, or 

 pustules, may have been frequently overlooked, yet none ever recovered without 

 more or less eruption or critical abscesses; but these differ from the pestilential 

 sort ; no otherways similar to the plague, but, like the small-pox, it is commu- 

 nicated by contact, by the air conveying the effluvia, which also lodge in many 

 substances, and are thus carried to very distant places. Unlike other pestilential, 

 putrid, or malignant fevers, it bears all the characteristic symptoms, progress, 

 crisis, and event of the small-pox ; and, whether received by contagion or 

 inoculation, has the same appearances, stages, and determination, except more 

 favourably by inoculation, and with this distinctive and decisive property, that a 

 beast having had the sickness, naturally or artificially, never has it a 2d time. 



XXXII. An Investigation of the Principles of Progressive arul Rotatory Motion. 

 By the Rev. S. Fince, A. M. of Sidney Coll. Camb. p. 546. 



The communication of motion by impact is well known to constitute a con- 

 siderable part of" that branch of natural philosophy called mechanics ; and 3»- all 

 our inquiries in it are directed, either to assist us in those operations which add 

 to the conveniencies of life, or to explain, for the satisfaction of the mind, those 

 changes which we daily see arise from the effects of bodies on each other, it 

 might naturally have been expected that the attention of philosophers would have 

 been engaged, first in the investigation of such cases as most frequently occur 

 from the accidental action of one body on another, before they had proceeded 

 to others less obvious. A little consideration will convince any one how seldom 

 it happens, in the collision of two bodies, that their centres of gravity and point 

 of contact lie in the line of direction of the striking body ; yet few writers on 

 mechanics have extended their inquiries any further than this simple case. It 

 must however be acknowledged, that the action of bodies on each other, in di- 

 rections not passing through their centre of gravity, affords a subject at once 

 curious in speculation, and useful in practice. 



I. Bernoulli was the first who published any thing on this subject. He found 

 the point about which a body at rest would begin to revolve when struck by 

 another body ; observing however tliat D. Bernoulli had also discovered the 

 same : he also mentioned the curve described by that point in the progressive 

 motion of the body, and directed a method of inquiry by which the velocities of 

 the bodies may be found after the stroke ; which comprehends all he has done on 



