422 A SHORT HISTORY OF SCIENCE 



Society, who afterwards, by their kind encouragement and entreaties, 

 engaged me to think of publishing them. But after I had begun to 

 consider the inequalities of the lunar motions, and had entered upon 

 some other things relating to the laws and measures of gravity, and 

 other forces ; and the figures that would be described by bodies at- 

 tracted according to given laws ; and the motion of several bodies 

 moving among themselves ; the motion of bodies in resisting mediums ; 

 the forces, densities, and motions of mediums; the orbits of the 

 comets, and such like ; I put off that publication until I had made a 

 search into those matters, and could put out the whole together. 

 What relates to the lunar motions (being imperfect) I have put all 

 together in the corollaries of proposition 66, to avoid being obliged 

 to propose and distinctly demonstrate the several things there con- 

 tained in a method more prolix than the subject deserved, and in- 

 terrupt the series of the several propositions. Some things, found out 

 after the rest, I chose to insert in places less suitable, rather than 

 change the number of the propositions and the citations. I heartily 

 beg that what I have here done may be read with candor ; and that 

 the defects I have been guilty of upon this difficult subject may be 

 not so much reprehended as kindly supplied, and investigated by new 

 endeavors of my readers. 



ISAAC NEWTON. 

 CAMBRIDGE, Trinity College, 

 May 8, 1686. 



( Translation by Andrew Motte. The Harvard Classics, Vol. 39, pp. 157-159.) 



G. AN INQUIRY INTO THE CAUSES AND EFFECTS OF THE 

 VARIOLA VACCINM, A DISEASE DISCOVERED IN SOME 

 OF THE WESTERN COUNTIES OF ENGLAND, PARTICU- 

 LARLY GLOUCESTERSHIRE AND KNOWN BY THE NAME 

 OF THE COW POX 



BY EDWARD JENNER, M.D., F.R.S., etc. 



[The first successful attempt and this wholly empirical to control smallpox 

 in the human subject was the art of Inoculation with the virus of smallpox itself, 

 a procedure derived from the East, and introduced about 1720 into Europe and 

 America. In 1796 Jenner laid the foundation of experimental medicine, immu- 

 nology and serology, by his work on Vaccination, i.e., inoculation with cow-pox, 

 in a paper bearing the above title. The first edition was published in 1798 and 

 the second, from which the following extracts are taken, in 1800.] 



