vol.. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 311 



pence you may be at in procuring lime, which even in the largest tan-yards can 

 amount but to a trifle, will be amply compensated by the saving of bai'k ; be- 

 cause lime-water so completely exhausts the bark, and makes it go so much far- 

 ther than when the ooze is made only of plain water. As a proof of this, you 

 may make a pretty strong ooze from the tan or spent bark, which you now con- 

 sider as completely exhausted, by infusing it in lime-water. 



IJC. Observations on the Populatioyi and Diseases of Chester, in the Year 1774. 

 By J. Hay garth, M. D. p. 131. 



The facts ascertained in the following tables prove Chester to be healthy in 

 such an uncommon degree, as will astonish those who are best acquainted with 

 the general state of mortality in large towns. In order to deduce satisfactory 

 and useful conclusions from these facts, it seems necessary to describe a few 

 peculiarities in the situation of this city, which probably contribute to produce 

 a salutary effect. The intelligent reader will remark, in the following account, 

 that the structure of Chester prevents, in an uncommon degree, 1 principal 

 sources of disease, stagnant moisture and putrefaction. 



Chester is placed on a red, sandy, mouldering rock, which forms a rising 

 promontory, whose summit is elevated exactly 100 feet above high-water 

 mark, and 40 feet above the adjacent country ; from this point the streets 

 have a gentle declivity every way to the edge of the rock, whence there is a per- 

 pendicular fall of many yards from every part of the town. 



The loose rock on which the town is built absorbs moisture : for being cut 

 into filtering stones, water soon passes through its pores. The principal streets 

 that meet in the centre of the city, are deeply excavated out of the rock, being 

 sunk 6 or 9 feet lower than the surface of the ground. By this structure the 

 foundations of the houses are kept perfectly dry, as the streets quickly drain off 

 the water, and the rock absorbs all the remaining moisture. For these reasons 

 the cellars in general are dry, a circumstance that greatly contributes to health. 

 Stagnant water in a cellar is probably very often the unsuspected cause of putrid 

 diseases : its pernicious influence seems to resemble, in some degree, that of 

 bilge-water in a ship. There is a form of building peculiar to Chester, called 

 the rows, which are covered galleries that make a complete communication 

 between most of the principal streets. The rows are always dry and clean, even 

 in wet and dirty weather ; they moderate the heat of summer, and the coldness 

 of winter. These uncommon advantages oftener tempt abroad persons of a 

 delicate and valetudinary constitution, whether they be engaged in business or 

 amusement ; by which they obtain the benefit of iVesh air and exercise, without 

 incurring danger from catching cold. 



The walls are near 2 miles in circumference, and surround the central part of 



