57 



a large scope of country north of the Iowa river, commencing with 

 the counties bordering on the Cedar river, and extending to above Du 

 buque, and probably to the north boundary of the State, in which 

 there are fine mill streams, with rocky bottoms and banks, with but 

 little bottom lands and no swamps. The mill dams flood no lands 

 and create no disease. I am indebted to Drs. Sales and Witter for 

 interesting descriptions and statements in reference to this section 

 of country. 



The county of Van Buren may be considered a type of the Des 

 Moines Valley, and with the exception of the river itself, it would 

 seem to be free from any permanent causes of disease. I am com- 

 pelled to rely on the statement of Nicollet as to the river itself, to-wit: 

 that it flows constantly in a deep valley, until near its mouth, where 

 it spreads over low grounds, that it has a uniform rocky bottom, and 

 that its current is almost as rapid as that of the Missouri. This 

 would indicate a health producing stream. But Dr. Flint informs 

 me that there is a long moss, which at low water becomes very abun- 

 dant, and getting dislodged b\ floods, or other accidents, is drifted to 

 the head of Fslands, or on to mill dams, and there undergoing de- 

 composition, is considered a very abundant source of autumnal fe 

 vers. What effect the State Improvements may have on the health 

 of this country must depend on the amount of submerged lands, and 

 the accumulation of this long moss already referred to. 



The whole eastern and southern portion of the State, with few ex- 

 ceptions, abounds with limestone suitable for building purposes. The 

 prevalence of lime is generally considered conducive to health. 



The valley of the Des Moines, that of Skunk, and many other 

 streams, abound in stone coal. The influence of beds of bituminous 

 coal are not known to me to be prejudicial to health anywhere. 



The county of Dubuque abounds in lead mines; but the working 

 of them as at present conducted, cannot be very injurious. Since 

 Dr. Horr in his communication does not even allude to the subject. 

 Doubtless, however, cases of colica pictonum occasionally occur. 



Our principal river towns may form a distinct class, and deserve a 

 seperate consideration. Their first settlement was followed by sea- 

 sons of sickness, often to all the inhabitants, sometimes none escap- 

 ing. This was owing to the usual prevalence of malaria from stag- 

 nant water, and drainage aggravated by badly built houses and by 

 poor living. So far as I am informed, our river towns are uniformly 

 and rapidly improving in their healthful condition. The better drain- 

 age resulting from the grading of our streets and the more thorough 

 attention to cleanliness, as well as the improved condition of our dwel 



