Licence: Public Domain Mark
Credit: The atmosphere in relation to human life and health. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![of air and ground. The eiiiissioii of orpinic particles IVoiii niai^lies and dryinfj edges of i)oo]s, etc. The amount of organic matter and number of microbes in the air in different situations, hours, and seasons, as, for instance, in malarious valleys and tracts, and on bills and house tops comi);ired with a height of 3 or 4 feet from the ground, on sandy malarious plains on still even- ings, in places subject to cholera, diarrhea, and rheumatism, in low meadows and by river banks at sunset in summer, in places some miles to windwiird and to leeward of great towns, in streets, in old and new bouses, in crowded places, in railway cars and in cabins, and in schools. An investigation of all the phenomena and physics of evaporation from liquid and solid surfaces. The development of electricity, the effects of differences of temi)erature, of surface tension of slight impurity and slight films of oily matter, the phenomena of the dust- free envelope, and the conditions of evaporation from the human body Avould be within the scope of the inquiry. The determination of the resisting power (1) in pure fresh air, and (2) in foul or rebreathed air in a room, of the various microbes con- cerned in various diseases of an infectious nature. The effect of dry- ness of air, of sunshine, of the presence of a minute trace of organic matter, of the character of the material, Avhether mineral or organic, on which they rest. The effect of ozone, of nascent oxygen, and of the vapors of various antiseptic or disinfecting substances. The capa- bility of growth of various disease microbes on culture material intended to imitate the organically contaminated walls or rooms, etc., and the discovery of means for preventing such growth and emission into the air of inhabited places. Examination and culture of microbes and experiment on microbes found on walls of closely inhabited rooms. Cultivation of microbes on size used for papering, and on paper, and on plaster. The observation of the number of microbes in air over vari- ous kinds of street pavement. Examination of systems by which the air of sewers and drains may be prevented from entering dwelling houses, and of means by which the drain may enter the sewer from underneath, so that the drain may effectually and permanently be sealed by contained water or sewage. A very interesting branch of research, and one to which little atten- tion has hitherto been paid, is the formation of ice crystals, snow, and hail. In the free atmosphere, beautiful crystals develop themselves in great variety, mostly hexagonal or six-rayed, but some few with three or twelve rays, and some of less regular shape. At least two hundred different shaped crystals have been observed and drawn, many of the most exquisite delicacy and regularity. Often a single shower yields several different species of snow crystals, but generally there is great similarity in the crystals which fall about the same time. The cause of the difference in shape has not been made out, and indeed is not likely to be fully accounted for by any means at our disposal, but the present](https://iiif.wellcomecollection.org/image/b21208724_0135.jp2/full/800%2C/0/default.jpg)
