VOL, v.] PHILOSOPHICAL TRANSACTIONS. 523 



jecture extend it to the river of Thames, where yet I think you can be my wit- 

 ness, that it has been observed several years to succeed accordingly. What va- 

 riety is on other coasts I am not certain, but from an account read in the Royal 

 Society in my hearing, about the end of the year 1667, I understand that about 

 Chepstow bridge they observe the like to happen about the beginning of March 

 and end of September, the one as much before the vernal as the other is after 

 the autumnal equinox, like as in our case it happens, which they call by the 

 name of St. David's Stream and Michaelmas Stream ; as we do those in Kent, 

 Candlemas Stream and Allhallond Stream ; and when seamen take so much no- 

 tice of particular tides as to give names to them, it is a great presumption, that 

 it is for some remarkable accident usually happening at those seasons. 



And if to this of the sun's or earth's be added that of the obliquity and eccen- 

 tricity of the moon's orbit, it will, if it do no good, at least do no hurt. And I 

 the rather think it may be considerable, because the earth and moon's appro- 

 pinquation and elongation do really alter the distance of the common centre of 

 gravity, (of the earth and moon) from the earth (rendering the earth's epicycle 

 elliptical) and much favours what M. Childrey observes of the moon in perigaeo. 

 And this is the sum of what I thought proper to return you upon those animad- 

 versions, being, &c. 



An Account of some Books. iV" 64, p. 2074. 



I. Dissertationes Medicae Tres: 1. De Causis fluxiis Menstrui Mulierum. 

 2. De Sympathia variarum Corporis partium cum Utero. 3. De Usu Lactis ad 

 tabidos reficiendos, et de immediate Corporis Alimento. Auth. Francisco 

 Bayle, Doct. Medico. Tolosae, 1670, in 4to. 



Upon the subjects here enumerated this author has no observations that can 

 interest the physicians of the present days. 



II. Historiae Generalis Insectorum, Johannis Swammerdami, Pars prima. 

 Ultrajecti, 1 669, in 4to. 



This curious and philosophical book, written in the Belgick tongue, treats 

 chiefly of these three things : 



First, It lays down the ground of all natural changes in insects, declaring, 

 that by the word change is nothing else to be understood but a gradual and na- 

 tural evolution and growth of the parts, not any metamorphosis or transforma- 

 tion of them ; which growth is here made to resemble, not only the increase of 

 other animals, but also the budding, knitting, and spreading of plants. And 

 here the author, having taken notice, that whereas ancient and famous writers 

 have esteemed and called the nympha among insects the change of that worm, 

 which carries the proper shape of the future little animal, and the chrjsalis or 



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