Proceedings of the Royal Society/. 279 



The principle of Mr. Jones's Hygrometer is essentially the 

 same with that of Mr. Daniell's, viz-^ to ascertain the tempera- 

 ture at which dew is deposited from the atmosphere. It differs 

 from Mr. Daniell's, however, in the frigorific action being ap- 

 plied immediately to the bulb of the thermometer employed to 

 measure the temperature. 



This bulb is of considerable size, and of a cylindrical form, 

 slightly flattened and extended at the end. The stem of the 

 thermometer being twice bent at right angles ; this end of the 

 bulb turns upwards. It is made of black glass, and is exposed, 

 but the rest of the bulb is covered with muslin; This being 

 moistened with ether, the mercury is cooled, and dew at length 

 settles on the exposed part, at which moment it is read off. 



Mr. Jones, after describing this instrument, alludes to an 

 objection to its use, drawn from the application of the frigorific 

 process to the lowei' part of the bulb, while the dew is deposited 

 at the upper. This objection, if realized, might be obviated by 

 inclining the bulb, so as to have its axis horizontal. But re- 

 peated trials have satisfied him of there being no occasion for this 

 precaution. 



A paper On the Nature of the Functions of Mortality ^ and 



on a Neio Mode of determining ike Value of Life Contingencies, 

 was communicated by Benjamin Gompertz, Esq., F.R.S. 



This paper, which is a continuation of former researches on 

 the same subject printed in the Transactions of the Royal 

 Society, was divided into two chapters. In the first the 

 author considers the nature of the law of those numbers in tables 

 of mortality which express the amount of persons living at the 

 end of ages in regular arithmetical progression. He remarks 

 first, that for short intervals the law approaches nearly to a de- 

 creasing geometrical progression, and that this must be the case, 

 whatever be the strict expression for the law of mortality, pro- 

 vided the intervals do not exceed certain limits. But he further 

 remarks that this property will be found to belong to very ex- 



