for the United States Geological Survey, but cheaper and simpler instruments can be made to serve almost as well. This instrument is best carried in a leather box worn upon the belt. The aneroid, if used, is carried in a leather case slung from the shoulder and passed under the belt so as to be shaken as little as possible. The hammer is most conveniently carried upon the person by slipping the handle through the belt, a 'pick' or prospector's form being specially secure in this position because of its long head. When riding the hammer is slipped under a strap on the side of the carrying frame of the rock bag.
Where observations must be frequently taken, as in detailed areal mapping, considerable time may be lost in finding a suitable support against which to rest the wheel. Bicycle manufacturers should be able to devise a light and simple support which can be carried with the wheel and quickly adjusted. In a region adapted to bicycle work, such as much of the Piedmont Plateau and the Coastal Plain of the eastern United States, as well as large areas in Europe, it is believed that a bicycle outfit such as is here described makes it possible to reduce greatly the expense and to divide by at least one-half the time necessary for mapping over that required if older methods of locomotion and transportation are employed. The inertia of long-established practise is, however, considerable, and geologists have been somewhat slow to adopt the newer methods. The small expense of such an equipment and the accessibility of the beautiful government maps make it possible for private and essentially amateur geologists, with the advantages of only a brief geological training and a moderate amount of experience, to collect valuable data within the area surrounding their homes, especially if these chance to be in a thickly settled part of the country.