139 



intended ; but, to render it advantageous, the recognition of the tra- 

 ditionary custom of peonage is necessary. A thorough code of 

 mining laws is also much to be desired, for however Avell the plan 

 of permitting miners to make their own regulations may be thought 

 to work in gold districts, it will never place silver mining on a solid 

 basis ; but cannot, on the contrary, act otherwise than prejudicially 

 to the interests of both miners and the State. 



There is but little doubt, that after a few years of proper devel- 

 opment, Arizona might become an important source of silver, al- 

 though its veins do not possess the great thickness of many of the 

 mines of Mexico, although the average richness of the ore is greater 

 and more concentrated. Still, it cannot be expected to produce 

 the brilliant results obtained in Central Mexico. 



August 19, 1861. 

 President in the Chair. 



The following communication was presented by Col. L. Ransom : 



DECLINATION OF THE MAGNETIC NEEDLE. 



Being connected with the United States General's Otiice in Cal- 

 ifornia from the commencement of the public surveys in 1851 until 

 1858, I became familiar with the field operations of the Deputy 

 Surveyor from examinations of the field notes and maps of surveys, 

 as returned from time to time. 



As the regulations of the General Land Office required the varia- 

 tion of the compass to be taken as often as once in each township, 

 (of six miles square) I became impressed with the great difference 

 in the variations bQtween the northern and southern portions of the 

 State, and at once determined to make a record of those differences. 



I therefore ruled a rough jnap to designate the township and 

 range lines, and from time to time entered the magnetic variations 

 as taken in each surveyed township and returned by the Deputy 

 Surveyors ; and since I left the Surveyor General's Office, I have 

 been enabled, through the courtesy of those having the surveys in 

 charge, to complete my notes and memoranda, so far as the public 

 surveys have progressed. 



From these, I have been enabled to present the Academy with 

 a small skeleton map of the State, on which are delineated the town- 

 ship and range lines, as they have been and are intended to be 

 established by actual survey, with fines of equal variation of the 



