The consequences of an insufficient and impure supply of water are deserving of the most serious consideration. The Reports of the Health of Towns Commission (1814 and 18451 contain much information on the first of the subjects; while the Reports of the Medical Officer of the Privy Council abound in facts relating to the second subject. Wo find that an insufficient supply leads to the person and clothes not being washed at all, or being repeatedly washed in the same water; to water for cooking being repeatedly used; to imperfect cleansing of house:; and streets; to the sewers becoming Clogged, and the air thus rendered impure. The natural result is—as in the case of a deficiency of pure air—a depressed condition of the general health, with a tendency to skin-diseases, ophthalmia, etc. ; while the imperfect cleansing; of the sewers favors the spread of typhoid fever and of choleraic diarrhea. We are indebted more perhaps to Mr. Simon's valuably reports than to any other source for the knowledge that a continually increasing class of cases is found to be connected with the use of impure water, the principal noxious iagredients being animal organic matter, especially when of fecal origin; vegetable orgimi3 matters, when derived from marshes; and some salts, except when in very small quantities, as sulphates of lime and magnesia, chlorides of calcium and magnesium, nitrates and nitrites of ammonia, etc. The alimentary mucous membrane is especially liable, 113 supposes, to be affected by impure water. Thus, dyspepsia, with such symp toms as partial loss of appetite, uneasiness or pain in the pit of the stomach, nausea and constip.ition, with occasional diarrhea, may be caused by water containing certain quan tities (probably about eight grains each per gallon) of sulphate of lime, chloride of cal cium, and the magnesian salts. Diarrhea may be caused by the use of many of the great North American livers, the Ganges. etc., where ninch clay is held in susliensiOn. Water contaminated With sewage, and containing suspended animal and especially fecal matter, is a common cause of an outbreak of this affection and even oT choleraic symptoms. Dissolved animal organic matters doubtless have a similar effect, but it is diffieult to distinguish between the actions of these and of suspended organic matters. Among other impurities known to oecasion diarrhea are fetid gases (suipliureted hydro gen), an excess of dissolved mineral matters and nitrate of lime; and on most persons, brackish water acts similarly. The effects which the selenitic well-waters of Paris exert on straierers are well known. There is abundant evidence to show that impute water is one of the principal causes of dysentery. The records of our army surgeons abound in illustrative cases. The deleterious effect of the impure water of Calcutta in inducing dysentery has been forcibly pointed out by Dr. Obeyers iu the Indian Annals for 1864.
In addition to the diseases affecting the alimentary mucous membrane of the tines, there are certain specific diseases which result from the use of impure water, as malariohs fetters of various forms, from the. use of the water of marshes;' typhoid fever, from water contaminated with sewage matters, or the special typhoid poison; clwlera, from water into which cholera-evacuations have made their way; and possibly yellozofever. (The relation of impure water to typhoid fever and cholera will be more fully noticed in a later part of this artiele.)' To the use of water unfit for drinking purposes are also ascribed epidemic boils from the presence of sulphureted hydrogen; disease of the bones, as exostosis, from an excess of carbonate and sulphate of lime; calculi (on, we think, iusntlieient evidence); goiter, from water derived from limestone and magnesian rocks; and entozoa of various kinds. Dr. Parkes sums up the department of his lifanual which
treats of water in a hygienic point of view with the. following- practical conclusions: "(t) An endemic of diarrhea in a community is ahno. t always owing either to impure air, impure water, or bad food. If it affects a number of persons suddenly, it i i probably owing to one of the two laet causes; and if it extends over many families, almost cer tainly to water. (2) Diarrhea or dysentery constantly affecting a community, or return ing periodically at certain times of the year, is far more likely to be produced by bad water than by any other cause. (3) A very sudden and localized outbreak of either typhoid fever or cholera, is almost certainly owing to the introduction of the poison by water; and the same fact holds good in cases of malarious fever. (4) The presence of lumbriei, guinea-worm, or buthriocephalas kilts, should always excite suspicion of the drinking and bathing water.":—Op..eit., p. 63.
After the two most important factors in relation to health, viz., air and water, Sour and CLIMATE occupy a secondary. although by no means unimportant place. As their practical bearing is less direct and universal, we will dismiss them briefly. Soil may affect health (1) by its conformation and elevation. Thus, among hills, the healthy spots are inclosed valleys, where the air must stagnate, and ravines. On plains, the most dangerous spots are at the foot of hills which store up water, unless a ravine cuts OffIlio drainage. (2) IrtTetation exerts an important influence. If we regard vegetation as divisible into herbage, brushwood, and trees, it may be laid down as a general rule, that herbage is always healthy, and in the tropics, is of great importance in cooling the ground, both by obstructing the sun's rays and by aiding evaporation; that brushwood is almost always bad, but that its removal may cause a temporary increase of malarious disease, on account of the disturbance of the soil; and that trees should seldom be removed, unless they decidedly interfere with the movement of the air, for in cold countries they shelter from cold winds—in hot, they cool the ground—and in both they may afford protection front malarious currents. The present condition of St. Thomas in the West Indies, which is now one of the most pestilent sites we are acquainted with, is mainly due to the insane destruction of its trees. The island of Mauritius, which has lately been visited by one of the most universal and destructive forms of fever ever recorded, has similarly suffered from the same cause. (3) The mechanical structure of the soil is of hygienic importance in various points of view. Thus. heat is very differently absorbed by ,differ ent soils under the same conditions of exposure. Assuming that the sand with a little lime has the maximum power of retaining heat, and that its capacity be represented by 100. then the capacity of clay will range from 76.9 to 66.7; while that or chalk will be 61.8, and that of humus as low as 49. Hence we see the comparative coldness of the latter soils as compared with sand. The capacities of these soils for absorbing and retain, ing moisture are in the reverse order.