450 Analyses of Books. [Dec. 



For the experiments on the twist of bars, we must refer to the 

 paper. 



The strengths of Swedish and English iron do not bear the 

 same proportion to each other in these experiments that they do 

 when we compare the trials of Count Sickingen with those made 

 at Woolwich, of which an account was given in the Annals of 

 Philosophy, vii. 320. From that comparison, the proportional 

 ■Strengths were as follows i 



English iron 348-38 



Swedish iron 549*25 



But from Mr. Rennie's experiments, the proportional strengths 



'are: 



English iron 348-38 



Swedish iron 449-34 



A very material difference, which ought to be attended to. 



VIII. On the Office of the Heart-wood of Trees. By T. A. 

 Knight, Esq. F.R.S. — It is sufficiently known that the trunk of 

 trees, after a certain age, is divided into two distinct substances, 

 called the alburnum and the heart-wood. The alburnum is next 

 the bark ; it is softer, looser in its texture, and lighter coloured 

 than the heart-wood. Some physiologists have supposed the. 

 heart-wood to be dead vegetable matter. But Mr. Knight ha» 

 always combated this opinion. The object of the present paper 

 is to prove that heart-wood, as well as the alburnum, serves as a 

 reservoir of nourishment which the tree lays up before winter. 

 This nourishment is employed in the following spring in forming 

 the foliage of the plant. 



IX. On circulating Functions, and on the Integration of a 

 Class of Equations of finite Differences into which they enter as 

 Co-efficients. By John F. W. Herschell, Esq. F.R.S. — As this 

 paper is incapable of abridgement, we must refer the mathema- 

 tical reader who wishes to study it to the volume of the Transac- 

 tions itself. 



X. On the Fallacy of the Experiments in ichich Water is said 

 to have been formed by the Decomposition of Chlorine. By Sir 

 H. Davy, LL.D. F.R.S. The object of this paper is to show 

 that the water formed in Dr. Ure's experiments, of which an 

 account was given in the last number of the Annals, was owing 

 to the hydrogen evolved by the union of the chlorine with the 

 metals combining with the oxygen of the litharge and alkali of 

 the glass, or with the oxygen gas, which happened to be present 

 in the tubes during the experiments. Of course the consequences 

 deduced by Dr. Ure from his experiments are fallacious. 



XI. The Croonian Lecture. On the Changes the Blood under- 

 goes in the Act of Coagulation. By Sir Everard Home, Bart. 

 V.P.R.S. — The author of this lecture is of opinion that the single 

 muscular fibres (if the expression be allowable) are composed of 

 the globules of the blood, which he says have an attraction for 



