598 PHILOSOPHICAL TRANSACTIONS. [aNNO 1755. 



the Phil. Trans of the r. s. N" 367. The first was sent by the Hon. Paul Dud- 

 ley, F.R.s. from New England, and the other was communicated by Dr. Wm. 

 Sherrard, f.r.s. By both these accounts it is very plain, that this species of 

 toxicodendron grows naturally in Virginia and New England, in as great plenty 

 as Carolina, where all the species are the most common under-wood, in the lands 

 which have not been cleared. He adds, that as these shrubs are so very com- 

 mon in our northern colonies, and the anacardium, or cashew nut-tree, is also 

 common in our southern colonies of America ; it were to be wished that the 

 inhabitants of both would make some experiments to collect this varnish, which 

 may not only produce much profit to themselves, but also become a national 

 advantage. 



XX Fill. On the Method of Constructing a Table for the Probabilities of Life 

 at London. By the Rev. ff'llliam Brakenridge, D.D., F.R.S. p. 167. 



The great Dr. Halley, who had a singular faculty of applying his mathema- 

 tical knowledge to the purposes of life, was the first who particularly attended to 

 this subject. In the year 1692, from the bills of mortality at Breslau, he reduced 

 it into a sort of science ; and gave a table of the probabilities of life, that hitherto 

 has been justly esteemed the most exact of any thing of the kind ; from which 

 he and others have deduced many propositions, that are highly useful. But a 

 doubt having arisen, whether that could properly, or with any accuracy, be used 

 by us at London, as we are in a different country, and perhaps in a different way 

 of life. Dr. B. has been at some pains to inquire into this, and satisfy himself 

 about the objections. And he imagines that he can now show how that table 

 may be altered, to suit our case with sufficient exactness. 



In the London bills of mortality, for the last 30 years, there is always added 

 an account yearly of the number of burials under each age, at the distance of 

 10 years, and of children more particularly under 2 years, between 2 and 5, and 

 between 5 and 10 ; which numbers are curious and useful. And though there 

 may sometimes be some inaccuracies and omissions, these numbers are as exactly 

 given as in our case can be expected : and what may be objected, is not so 

 much to the incorrectness of them, as to what arises from our circumstances, 

 that will not allow them to be proper to show the probabilities of life in all its 

 periods. 



But if we compare the numbers of the dead, in the several periods at Breslau, 

 with those at London, we shall plainly see that the former show the decrements 

 of life in a natural and regular way, and free from the difficulties and objections 

 . found in those of London. In the infant state, under 2 years of age, there is a 

 5th lost by death ; but afterwards, as they gather strength, the deaths are di- 

 minished till between 10 and 20 ; and from that age the mortality gradually 



