VUL. XLl.] PHILOSOPHICAL TRANSACTIONS. -425 



nical formation of a vortex is impossible ; 2. That a vortex, though once formed, 

 cannot be lasting ; 3. That it is not sufficient for explaining the celestial phaeno- 

 mena. After labouring these points, at great length, in the details of which it 

 is now of no use to follow this author, he at last concludes that, therefore the 

 vortex is every way impossible, ami insufficient in natural philosophy. Its me- 

 chanical generation is impossible ; it has only an axifugal force, and not a cen- 

 trifugal and centripetal force, as it should have ; and even if it had, it cannot 

 defend itself equally on all sides. It is not sufficient for explaining gravity, and 

 its properties ; it destroys Kepler's astronomical laws. What more can be de- 

 sired, in order to conclude with Sir Isaac Newton? ' Itaque hypothesis vorticum 

 ' est impossibile, et cum phaenomenis astronomicis omnino pugnat, et non tarn 

 • ad explicandos quam ad perturbandos motus ccelestes conducit.' a. e. d. 



j^n Account, . by David Hartley, M. B. F. R. S. of Dr. Trevo's Dissertation con- 

 cerning the Differences of a Human Body bejore and after Birth, intitled. 

 Diss, epistolica de differentiis quibusdam inter hominem natum et nascendum 

 intervenientibus, deque vestigiis Divini Numinis inde colligendis. Jo. Georgia 

 Kramero inscripta. Cum Tab. jEn. Aut. Christoph. Jacobo Trew, Nori- 

 bergice, 1730, Ato. N° 457, p. 436. 



There are, according to Dr. Trew, 2 remarkable observations, which animal 

 bodies suggest, 1st. That the same general ends are accomplished in different 

 animals by all the possible varieties of means. 2dly, That animal bodies are 

 machines, which produce in themselves all those changes, that are necessary 

 for their preservation and well-being. Thus the same general ends of chylifi- 

 cation, circulation, secretion of bile, &c. are accomplished in different animals 

 by organs that differ considerably from each other ; and in the same animal the 

 body of the foetus is very different in its structure from that of the adult, at the 

 same time that this difference is effected by the body itself, each subsequent 

 variation, the natural and mechanical consequence of that which immediately 

 preceded, and the whole conducted in the best possible manner for tlie welfare 

 and happiness of the animal. 



The author's design in this dissertation, is to consider those differences of a 

 human body before and after birth, which affect the circulation of the blood. 

 And for this purpose he has given us 78 v^ry curious and accurate figures of 

 the parts relating thereto, such as the heart, and trunks of the great blood- 

 vessels, the liver, the vena portarum, the umbilical chord, &c. subjoining to 

 them a very minute and precise explanation of each. The work contains 

 numerous anatomical disquisitions; which will be best read in the book itself. 



VOL. VIII. 3 I 



