VOL. XLVIII.] PHILOSOPHICAL TRANSACTIONS. 541 



that this cause was the most prevailing. But whatever be the cause, it seems 

 plain, that it could not be the late French war, as some imagine. For, by what 

 was shown above, there has been a decrease of 56000 since the year 1749, after 

 the peace ; but if the war had been the cause, there ought rather to have been 

 an increase after it. And as in the whole, we could not have lost more than 

 150000 in the war, by land and sea, of which there was not one-fifth, or 30000, 

 taken from about the city ; this can never account for 64000, the decrease before 

 the year 1748. In the former war, between 1702 and 1711, the city never de- 

 creased, but continually increased : from which one would imagine that the last 

 war could not diminish its numbers. 



Nor can this decrease in the bills be accounted for, from a greater number 

 than formerly leaving the town in summer ; because it does not appear that 

 there is a greater number of such, than was 1 years ago. And if it could be 

 allowed that the number was greater, it can never be thought that it can amount 

 to 120000 more than in the year 1743. • 



It is true, this decrease may appear surprizing to some, when they see the 

 number of new buildings in Westminster, continually increasing ; but then, on 

 the other hand, it is likewise to be considered, that there are a great number of 

 houses enlarged, or rebuilt, instead of 2 or 3 others, as mentioned above ; and 

 others falling in and empty, about the eastern parts of the city : so that for the 

 last 20 years the inhabitants seem only to be moving, from the eastern to the 

 western parts of the town, and not increasing. 



XCVI. On a large Calculus found in a Mare. By Mr. JVm. Watson, F, R. S. 



p. 800. 



This stone was composed of different laminae, and its figure is that of an ob- 

 late spheroid, whose greatest diameter is 84- inches ; its lesser 8 inches. Its 

 surface is extremely regular, but it appears in several of its parts, as though it 

 had been corroded by some acrid menstruum ; and in a place or two, where the 

 external lamina is quite worn away, and the lamina immediately underneath it 

 polished during its continuance in the mare, the calculus has great resemblance 

 in colour to occidental bezoar. 



It weighed in air 15 lb. 12 oz. Avoirdupois ; in water 6 lb. : so that its specific 

 gravity to that of water was nearly as 8 to 5. So that it is not only considerably 

 lighter than any fossil petrifaction, but much more so than many animal ; some 

 human calculi, when fresh extracted, being to water as 2 to 1. 



With regard to its bulk, it is the largest he remembered to have been ob- 

 served, except one presented to the r. s. in the year 1737, which was taken out 

 of the stomach of a dray-horse, belonging to Sir Henry Hickes, Knt. at Dept- 

 ford, and which weighed 1 9 lb. Avoirdupois, exclusive of the outward shell or 



