THE TOPOGRAPHIC SURVEY OF MICHIGAN. 157 



reference to differences in elevation, in exposure to light, in range of 

 teniperatnre, in Imniidity and still other conditions, applies to hillsides 

 as well as mountain slopes. It is modified, loo, by dilferences in latitude, 

 and is dependent in a conspicuous way on position with reference to seas, 

 lakes, and streams. In brief, a biologic survey is concerned primarily 

 with the distribution of plants and animals. Commonly such distribu- 

 tion is termed geographic, but from what has just been stated, it is evi- 

 dently topographic as well. In the ideal biologic survey, the distribution 

 of each species of plant and animal with reference to both geographic 

 position and elevation, needs to be accurately known. To record such 

 data, and discover the causes which control distribution, or, in other 

 words, to learn the conditions on which life depends, and hence be able 

 to modify it or strive to exterminate noxious forms, an accurate map 

 showing the relief of the country studied, the distribution of water bodies, 

 the inclination of land surface, etc., is a primary requisite. Without such 

 a map a critical biologic survey of any extensive region is impossible. 

 Dela}' in making such surveys means continued exposure to unseen ene- 

 mies, and neglect of opportunities to utilize benign agencies which are at 

 our command. 



A biologic surve}' of Michigan was embraced in the plans of Douglass 

 Houghton, in 1837, for the study of the resources of the State, but not 

 carried into effect. Up to the present day no adequate study of the native 

 plants and animals of Michigan, or of the species introduced and their 

 influence, wdiether harmful or beneficial, has been made. This matter is 

 now commanding attention, and the first step in the desired direction, 

 as all biologists Avill agree, is the preparation of an accurate topographic 

 map of our broad domain. 



One phase of biologic study relates to the diseases of men. In ]Michigan 

 this subject is noAv in part, entrusted to the State Board of Health. Among 

 the aims of that organization is the discovery of the ways in which con- 

 tagious diseases are disseminated, the influences of drainage on health, 

 the dangers resulting from the pollution of streams, the geographic dis- 

 tribution of diseases, etc. In these and other related subjects pertaining 

 to medicine and hygiene, a knowledge of geographic conditions is plainly 

 of fundamental importance. This necessary preliminary information, 

 however, cannot be had by the guardians of health in IMichigan, until a 

 topographic map of the State is available. With such a map in hand, 

 the facts now known concerning the relation of diseases to environment 

 could be clearly shown, and much aid afforded in tl;e search for still 

 hidden causes of bodily ailments. 



To Farmers : The possibilities of agriculture are determined jnainly 

 by soil and clinmtic conditions. The better these are known and the 

 better this knowledge is applied, the more successful the results. To 

 furnish this knowledge, the Agricultural Department in Washington is- 

 sues thick volumes filled with the results of soil survey, and accompanied 

 by portfolios of maps on which soil conditions are indicated; and the 

 United States Weather Bureau each year, each month and each day, sends 

 out maps on which climatic and weather conditions are graphically re- 

 corded. Both in the gathering of these important data and in their dis- 

 tribution ma])s are essential, and the better the maps, the better will be 

 the results. In the study of soil conditions more definitely perha])s than 

 in related branches of research, is the influence of relief and, depending 

 on the relief, of drainage and distribution of soil-moisture, to be taken 



