But with all due deference to these learned and ingenious gentlemen, we have in the hermetically closed wards, heated by a Galton fire-place, of the small-pox hospital described in a paper which the author of this had the honor of reading before this Society in January, 1882, an apparatus amply sufficient to accomplish the same purpose as the above described more costly and pretentious structures. No one can doubt but that the passage of the foul air over the flame and through the ten feet of iron pipe of the Galton fire-place would totally destroy any germ of small-pox, especially if our common western bituminous coal, with its high percentage of sulphur, is used; for experiments in England have shown that by burning sulphur in a disinfecting stove (Nelson's) clothing may be disinfected in ten minutes, and at so low a temperature as 175° F.

THE

GEOLOGY AND TOPOGRAPHY OF IOWA

IN A

SANITARY POINT OF VIEW.

PREPARED BY

P. J. FARNSWORTH, M. D.,

FOR THE

IOWA STATE BOARD OF HEALTH.

GEOLOGY AND TOPOGRAPHY.

THE GEOLOGY AND TOPOGRAPHY OF IOWA IN A SANITARY POINT OF VIEW.

BY P. J. FARNSWORTH, M. D., CLINTON, IOWA.

The geological and topographical features of a country determine, in a great measure, its sanitary conditions or capabilities. They characterize the soil drainage and water supply, the temperature, moisture, and other qualities of the air, and the kind and quantity of the productions. They are, therefore, important elements in the consideration of the health and prosperity of a State, and merit a careful study. A subject so extensive requires a large collection of facts, some of which are accessible, others are yet to be obtained. We can, therefore, only treat it in a general manner. We can glance at primitive conditions and draw some probable conclusions from them; but a more extended record of observations must be made to determine the effects of added settlement and cultivation.

If we go back for a period of a little more than fifty years, the Territory of Iowa was in a state of nature; it had primitive soil and virgin prairie. It then became open to civilization, to men who dispossessed the nomadic Indians and the roving buffalo, who were to cultivate the earth, build towns and cities, and render their surroundings sanitary or unsanitary, as their knowledge or ignorance prompted them. In fifty years the whole State has been brought under cultivation, the face of nature changed, the soil upturned to the sun, the marshes drained, trees planted, and the vegetation altered. How far the natural surroundings are affected by artificial conditions must be determined by facts in process of accumulation. We are to consider the natural features, the geology and topography, and their relations. Iowa is a part of the great inter-continental plain or plateau of North America. In shape it is nearly a parallelogram; its northern boundary is 43°, 30', north latitude; its southern, 40°, 36'; its eastern and western boundaries are the two great rivers of the continent, on on the east touching 90°, 30', west from Greenwich, and extending to

96°, 30', west. From north to south it is 200 miles; from east to west about 300 miles. It has an area of a little over 55,000 square miles, or of arable land over 35,000,000 acres. Originally it was a uniformly level sea bottom, gradually coming to the surface. In some great convulsion of nature it was elevated above the ocean, and inclined toward the southeast, favoring its drainage and exposure to the sun. Its highest part is near the northwest corner, where it is 1,700 feet above the sea; its prairie level at the southeast is about 600 feet. A slight fold or flexure gives a decline to the west of a small portion of the State; still, on a line drawn through the middle of the State from east to west, the Missouri flows in a valley of erosion as deep as that of the Mississippi, but in a bed 425 feet higher. Thẻ underlying rocks are of two or three geologic ages, but of not a greatly varied composition. They were covered with a pretty uniformly deep layer of drift composed of argillaceous material. Then came a period of erosion, and the rivers formed plains and channels through the drift and into the underlying rock in some places. There are evidences of a submergence and a filling up of the old water courses, after which the rivers found their old channels again, or formed new ones, leaving the modified drift on their banks, or in their abandoned courses. The direction of the drainage follows the