SCIENCE.

Evening Star, Issue 3777, 2 April 1875, Page 3

SCIENCE.

{Frm ear own avm&tndeni.) Pabm, December 98. Dr Fonesagriero’a werk on the Hygiene and salubrity of cities Is very interesting. He shows that the more a eity is pepulous and attractive, the more it tends to draw towards it the inhabitants of the country districts. Cities having a rocky base are moat salubrious, as presenting the abserption ef water, and on the other hand a olay sub-stratum is unhealthy for opposite reasons. Holland is situated twelve feet belew the level of the sea, and its chief cities are built on piles. The coldness ef the climate there proves a safeguard to health,just as Venice, built in a lagoon, with 150 eanals for streets, is protested from fever, by its north-easterly winds and the daily ebb and flow of ths tide. The highest habitation on the globe is the sonvent of Thibet, some 16,500 ft in altitude. Latitude equal, cities are a few degress warmer than the country, the materials of the houses and streets having the property of retaining heat. The heat generated by animal life in Paris is estimated as equal to the 78th part of what the city receives during ten hours ef sunshine; vegetable life on the contrary absorbs heat, and gives off much water by transpiration. There are 164 cities in the world with not less than 100,000 inhabitants, and the total urban popuLatieu of the globe is estimated at 90 miluons, or the 28th part of the world's inhabitants. Zn Paris there are 147 people to the square sere, in London 46; and 33 and 8 tenants, respectively, per house. Upwards of 46 per cent, of the site of Paris consists of open apace, and if the Bois of Vincennes and Boulogne, just at the gates, be excluded, the arteries for aeration would be about 29 per cent. Paris has seme 103,000 trees iu the acting as so many vertical drains. In warm climates the streets are narrew and the heroes lew, se as to keep eff the direct rays ef the sun ; In celd climates the streets are wide and the houses high. In Paris the law compels the height of a house to be in proportion to. the width ef the street, and the streets are paved, as being cheaper to keep clean and in repair, as well as superior for traetieu. Macadam has been nearly banished, and wood pavement has been relinquished, as, in drowning the noise of vehicles, it has produced innumerable accidents. Asphaltam is excellent whore the streets are level. Paris consumes as much gas as the whole of France, exacting in its manufacture half a million tens of eeal, being the thirtieth of the total of the production ef the French coal mines. The daily eensumptiou of water is 175 quarts per inhabitant, soen to be raised to 216. For drinking purpoees ram water is excellent, provided It can be preserved in good water-tight tanks, as at Venice. Well-water is strongly condemned, as being the source of fovere and dysentry, and the supply from artesian wells is only good when the source is profound, The average duration of human life is a little longer in the country than In the town, and the death rate of London is a little less than that of Paris, but then the density of occupants per house is, as we have seen, eight m the former city and thirty-two in the latter. 1® ® TOJ 7 capital in the world it has been established that fever and consumption are most frequent, as the quarters of the CHty are most densely populated, and the same truth has been established in hospitals: the greater the number of patients the higher the deathrate.