28 The Ohio Journal of Science [Vol. XIX, No. 1, 



Such definitive data as could be drawn from the immediate 

 vicinity were in most cases supplemented by compass bearings 

 on distant objects. When a station commands a view of the 

 surrounding mountains or similar features, such bearings 

 are the most permanent marks that can be used for its location. 

 In other cases the bearings were taken on blazed trees, which, 

 if uncut, will stand for several centuries, w^hile even if cut, the 

 stumps will persist for a long while. Theoretically compass 

 bearings in two directions fix the location of any point, but in 

 practice the method is open to considerable objection. It is 

 very easy to take compass bearings from any point, but it is 

 much more difficult to return with the compass and pick up a 

 station from the readings. Pocket compasses, with which 

 the bearings were taken, are not instruments of precision, 

 moreover, and it is doubtful whether the instrument would 

 always duplicate its readings at the same station. Nevertheless,, 

 it is believed that such compass bearings will be of considerable 

 assistance in locating the stations after the face of the country 

 shall have undergone considerable change. 



ADVANTAGES OF PHOTOGRAPHS OVER HAND MAPPED 



QUADRATS. 



The most satisfactory means of locating a station, con- 

 sidering all things, is a photograph taken so as to show the 

 relation of the station to distant objects. Such bearings fix the 

 position of the camera with a considerable degree of precision. 

 In some cases, it has been found desirable, for example, to 

 duplicate a photograph taken soon after the eruption, which 

 came into our possession with no data as to location except that 

 furnished by the picture itself. Where the general location of 

 the picture could be guessed, it was found possible to fix its 

 exact location within a very few feet. It is believed, therefore, 

 that the photographs are the most valuable means of locating 

 the stations, containing as they do, much data not susceptible 

 of description. (See pages 4 and 5). 



In planning for the work before reaching the field, it was 

 assumed that the best form of vegetation station for the work 

 would be the meter quadrat developed by Clements. Experience 

 showed, however, that the ground covered by a definitely 

 located photograph makes a more satisfactory station. The 

 photograph possesses several distinct advantages over the 



