VOL. v.] PHILOSOPHICAL TRANSACTIONS. 4^ 



Avhich was done to avoid confusion, as well as too much labour and expence of 

 time in the engraving. 



The Reflections relating to Medical Springs, iV" 52, considered. 

 The Indications of some healing Springs remarked; with an Account 

 of some such Springs in England, which confrm the Indications; 

 and of others obiter. By Dr. J. Be ale. N" 5J, p. 1154. 



Of a piece with the other chemical papers of this author, prolix in the ex- 

 treme, and wholly uninstructive. 



Some Observations, Directions, and Inquiries concerning the Motion of 

 Sap in Trees, in pursuance of ivhat was formerly bfigun therein, 

 about the latter end of 16*68, and the next following Spring. By 

 Dr. EzEREL ToNGE, and Francis Willoughby, Esq. N° 5J, p. 1 165. 



After the inquiries and remarks of Dr. Tonge, on the difference between his 

 experiments and former ones, Mr. Willoughby adds as follows : — 



It is no wonder that Dr. Tonge's experiments, concerning the bleeding of 

 the sycamore, do not agree with ours, they being made in a different season ; 

 his in February, and ours towards the end of March, viz. the cold which 

 caused the increase of the bleeding in the sycamore and walnut, happened upon 

 the 23d, 24th, 25th, 26th of March ; and one sycamore, which ceased to bleed 

 from the 1 Ith of the same month, bled afresh copiously from wounds that had 

 been made so long before : the buds before the cold were just ready to open into 

 leaves, and the sap had begun to coagulate above a fortnight before. This 

 year, making incisions in the sycamore and common maple, in January, imme- 

 diately on the relenting of the first frost, we found that they both bled, and faster 

 as the weather grew hotter, nor did the succeeding cold promote, but rather 

 hinder their bleeding. So that the learned doctor most ingeniously conjectures, 

 that the ascent of sap in trees depends on a certain degree of heat, sufficient to 

 raise, but not to coagulate their respective juices. In those months wherein 

 the heat ordinarily falls short of that degree, an accidental heat or warmth of 

 weather promotes the bleeding ; but in those months wherein the ordinary 

 temper of the air exceeds that degree, an extraordinary fit of colder weather 

 makes them bleed again. The experiments concerning the northern and 

 southern sides of sycamores were made at the same time ; and are well solved 

 by the same hypothesis. 



In walnut trees, we never yet found that heat promoted their bleeding, but 



