18 THE UNITED STATES GEOLOGICAL SURVEY. [buil.227. 
Section of Instruments. 
To this section are intrusted the details regarding- the purchase of, 
accountability for, and repairs of all instruments used by the Survey. 
The clerk in charge is designated custodian of instruments. 
When the Survey was organized the stock of instruments was very 
small and no particular custodial method was observed. Their aggre- 
gate value was perhaps $10,000, while now the valuation approximates 
$90,000. Those used by the topographic force were under the control 
of the chief topographer, who supervised their purchase and their 
issue to the field parties and attended to the necessary repairs. As 
operations were extended the stock of instruments so increased and 
the wear and tear assumed such proportions that a custodian for all 
classes of instruments was designated and an instrument shop was 
established for their systematic repair. This shop was continued 
until a reduction in appropriations for the topographic branch in 
1890-91 necessitated its abolishment. Shortly after this a change was 
made in the administration of the topographic branch, when the duties 
of the chief topographer were delegated to the section chiefs, and one 
of their number took charge of the purchase and repair of instruments, 
the custody remaining as before. Repairs of such instruments as 
actually needed attention were then made annually by contract with 
instrument makers. This method continued for several years, when 
the duties connected with the purchase and repair of instruments were 
transferred to the custodian, and a separate allotment was made to 
him for the purpose of attending to these details without drawing on 
the allotments for the various topographic sections. 
When plans are determined upon for field work an estimate of the 
instruments required is furnished to the custodian of instruments, 
and it becomes his duty to see that the necessary articles are forth- 
coming when needed. Jn the topographic branch sufficient stock is 
kept to meet, as far as possible, any unforeseen conditions, but in the 
geologic branch instruments are obtained for each field party as occa- 
sion arises. If the stock is not sufficient it is augmented by purchase. 
The section chiefs determine what types of instruments will be the 
most serviceable, and the instruments are purchased when and where 
the best interests of the Survey will thereby be subserved. They are 
issued to the party chiefs upon requisition and are charged to them on 
memorandum cards. 
When instruments are transferred from one party to another in the 
field, a special invoice card is made out in duplicate and exchanged 
between the persons or parties involved, and the duplicate, acknowl- 
edging the transfer, is sent to the custodian, so that the proper entries 
may be made in the records. 
When practicable, separate parts of the instruments used are kept 
