fuller.] COLLECTION OF WELL RECORDS AND SAMPLES. 27 
The results of the work may be summarized as follows: 
Approximate number of persons returning samples, 200. 
Number of wells represented by complete sets of samples, 111. 
Number of wells represented by incomplete sets of samples, 190. 
Total number of samples received, 3,945. 
Records received in Survey notebooks, 139. 
Records received in other ways, 230. 
The scientific results include detailed records from 111 wells. Of 
these nothing need be said, their character being indicated by the 
present report. 
METHODS OF WORK. 
A number of States have, as a part of their work, undertaken a 
more or less systematic collection of deep-well records. The Second 
Geological Survey of Pennsylvania especially gave great attention to 
this feature, employing several men on the work of collecting and 
tabulating well records, of which several thousand were published. 
In .some cases observers selected by the State survey were stationed at 
certain important wells to insure the collection of samples and the 
taking of accurate measurements. A great number of well records 
have also been independently collected by geologists throughout the 
county for the information they throw on stratigraphic and other 
problems, and a considerable number of them have been published, 
often constituting contributions of great importance to those inter- 
ested in the occurrence of oil, gas, brines, and potable waters. The 
present system of the United States Geological Survey is believed to 
be more extensive and comprehensive than any previously put in oper- 
ation for the collection of well records and samples, and it has been 
thought desirable to put on record a description of the plan, for the 
benefit of those persons or organizations who may desire to conduct 
similar work in the future. 
It being manifestly impossible, because of the great expense 
involved, to place observers at the various wells, it was necessary to 
arrange for cooperation on the part of drillers throughout the coun- 
try. This cooperation could in general be expected only when the 
drillers should be substantially benefited by the work, and conse- 
quently in the development of the plan this point was kept con- 
stantly in the foreground. Arrangements were made whereby such 
questions as the drillers should submit in regard to their work would 
be promptly attended to, and records interpreted or samples examined 
on request. In return the driller is requested to furnish written records 
of his wells and samples of materials penetrated, his assistance to be 
acknowledged in the reports on well records, issued annually. 
