238 PHILOSOPHICAL TRANSACTIONS. [anNO 1668. 



pancreas, and that he never observed any effervescence to take place on mix- 

 ing acids with the bile ; but that in such experiments a precipitate was thrown 

 down (in the form of a coagulum*) similar to the precipitation of lac sulphuris 

 by acids. Hence he conjectures that the bile is subservient to chylification, by 

 correcting the acid fermentation of the food.-|- 



On the Variety of the Annual Tides in several Places of England. 

 By Dr. IVallis. N° 34, p. 652. 



In my Hypothesis for Tides I cast the annual high tides not on the two equi- 

 noxes, about the 1 1 th of March and September, nor yet on the apogee and 

 perigee of the sun, about the middle of June and December, but as proceeding 

 from a complication of those two causes, on a middle time between the perigee 

 and the two equinoxes, as is the greatest inequality of the natural days, pro- 

 ceeding from a complication of the same causes. And particularly for the coast 

 of Kent, about the beginning of November and February ; which agrees with 

 observations on those coasts. 



The last year an account was brought us of the annual high tides on the 

 Severn, and at Chepstow-bridge, to be about the beginning of March and the 

 end of September. Which though they agree not with the particular times on 

 the coast of Kent, yet in general they agree thus far, that the one is about as 

 much before the one equinox as the other is after the other equinox. You now 

 acquaint me with high tides about February 22, about the coast of Plymouth, 

 which is later than that of the coast of Kent, but sooner than that on the Se- 

 vern. And I doubt not but in other parts of the world will be found other 

 varieties. 



The reasons of these varieties are to be attributed to the particular position of 

 those parts, rather than to the general hypothesis. The general hypothesis of 

 the earth's diurnal motion, from west to east, would cast that of the waters, not 

 following so fast, from east to west ; which causes the constant current within 

 the tropics where the circles are greatest, westward from the coast of Africa to 

 that of America, which is also the cause of the constant eastern breeze blowing 

 in those parts. But the sea thus beating on the coast of America, is cast back 

 as with an eddy on either hand, and consequently returns from the American 

 shore eastward towards the coast of Europe ; where, the parallel circles to the 

 equator being less, and consequently the diurnal motion slower, it doth not cast 



* The precipitate here mentioned would consist of albumen, and perhaps some of the resinous 

 parts of the bile. 



+ This idea of bile correcting the acid fermentation of the food is consistent with its known com- 

 position, soda being obtained from it by chemical analysis. 



