516 POPULAR SCIENCE MONTHLY. 



data, that is, the visiting and examination of a great number of rock ex- 

 posures well distributed over the area, and the careful location of each 

 upon his topographical map, with observations indicated by special char- 

 acters and colors. Where the region is thinly settled and roads are few, 

 access will be difficult and the location of exposures doubly so, since no 

 well determined points upon the map will generally be found near at 

 hand from which to fix direction or to measure distance. In the com- 

 paratively thickly populated Atlantic section of the United States there 

 will, however, be found large areas within which the highways form an 

 elaborate network, and the location of outcrops will here be compara- 

 tively easy; a road corner, a sharp bend of a highway, a house, or other 

 characteristic landmark being generally near enough to furnish a basis 

 of measurement. It is for a study of such areas that the present paper 

 is especially intended. 



In the past the field geologist engaged in areal and structural work 

 has depended either upon his own power of locomotion or upon the use 

 of a saddle horse or a team. In the northeastern United States the 

 numerous fences restrict his use of a horse to the highways themselves, 

 and the difficulty of hiring suitable saddle horses has practically elimi- 

 nated them from consideration. When teams are used they must very 

 frequently be left while rock exposures are sought or examined, and the 

 time thus lost in hitching in suitable places is very considerable. 

 Further, a horse requires food and water, protection from flies, etc., and 

 its hire varies from one to three dollars per day. 



The advent of the bicycle has greatly facilitated the study of regions 

 where roads are frequent, though geologists seem to be slow to appre- 

 ciate its advantages. The increasing number of official government or 

 State geologists, of university professors, and of teachers and students 

 generally who engage in geological work may well excuse one for urging 

 the advantages in effectiveness, in cheapness and in comfort of a prop- 

 erly equipped bicycle for this and similar forms of scientific work. One 

 of the greatest of these advantages arises from the attached cyclometer, 

 which if read and recorded at road corners and other landmarks affords 

 one at all times either a perfect location (in case an exposure is found on 

 the highway), or a convenient base (if an excursion must be made away 

 from the road). 



The most convenient form of cyclometer for geological work is one 

 which can be attached to the axle of the forward wheel of the bicycle be- 

 tween the prongs of the fork. The slight disadvantage of being com- 

 pelled to bring the wheel to a definite position before reading the cyclom- 

 eter is small when compared to the danger of injuring the usual form 

 through the falling of the wheel or from contact with objects by which 

 the wheel is left supported. It is, moreover, frequently desirable to 

 ship the wheel as baggage on railway trains, and it is generally better on 



