VOL. III.] PHILOSOPHICAL TRANSACTIONS. 3lQ 



seems probable, that drawing sap constantly from trees every year, will not hin- 

 der their growth in body, branches, leaves, nor fruit, to any great prejudice ; 

 for pulsion will still supply juice into the emptied pores, till their capacity be 

 filled. 



It is possible also, that trees may grow better, and give more fruit, if the 

 right art of drawing sap be found out for that end; as some persons grow fatter 

 by often bleeding. If plenty of sap drawn from trees hinder at all, it seems 

 probable, that it will hinder growth of fruit, leaves, or uppermost shoots in tops 

 of trees, and yearly shoots in extreme parts. And hence we have a probable 

 reason of suckers robbing fruit, viz. because till the whole tree be filled with 

 sap, the fruit cannot be served in the uttermost branches. — Wherefore not only 

 suckers, but all superfluous not-bearing branches are to be carefully cut away 

 before, or at the entrance of the spring. 



An Extract of a Letter of Mr. James Gregory to the Publisher, con- 

 taining some Ohservations on M. Huygens' Letter, printed in Vin- 

 dication of his Exame?i of the Book entitled Vera Circuli et Hyper- 

 holcB Quadratura, N" 44, p. 882. 



See N° 37, p. 268 of this Abridgement. 



Extract of the Anatomical Account, written and left hy the celebrated 

 Dr. Harfev,* concerning Thomas Parr, who died in London at 

 the Age of 152 Years and 9 Months. iV° 44, p. 886. 



This account is annexed to a book, lately published in Latin by Dr. John 

 Betts, one of his majesty's physicians in ordinary, and fellow of the London 



• It is not possible to do justice to the memory of the great Harvey within the limits of a note. 

 His life will perhaps be inserted in the miscellaneous volume intended to be added to this Abridge- 

 ment. In the mean time, in place of a biographical sketch, w^e shall lay before our readers a sum- 

 mary account of the circulation of the blood, as explained and demonstrated by him in his immortal 

 work, entitled Exercitatio Anatom. de Cordis et Sanguinis Motu, first published in l528 ; though he 

 had announced, several years antecedent to this publication, the leading facts belonging to this im- 

 portant discovery, in the lectures which he delivered before the college of physicians. In tlie above- 

 mentioned treatise (the abstract of which here given is taken from the account of Harvey prefixed to 

 tlie edition of his works by the London college) he shows, by experiments made on living animals, 

 that the motion of the heart is performed by the contraction of its muscular fibres ; that die auricles 

 contract first, and thereby propel the blood into the ventricles ; then the ventricles contract, w here- 

 by the blood is driven into the arteries j being prevented from returning into the auricles by die situa- 

 tion and connexion of the valves. Now as by the repeated contractions of the ventricles more blood 

 is constandy propelled into the arteries than can be supplied by nourishment thrown into the veins 



