(F.) 



EAKLY OBSERVATIONS UPON MAGNETIC VARI- 

 ATIONS. 



By Franklin B. Hough, of Lowville, N. Y. 



Although, the theory and laws of secular changes in the declination 

 of the magnetic needle are receiving careful study at various special 

 observatories, we cannot hope to arrive at precise results until our 

 records have extended over a considerable period of time. Early 

 observations will, therefore, when made with sufficient care, possess 

 great interest, as affording subjects for comparison, besides the positive 

 data which they afford in deciding disputed boundaries, where the 

 decision may depend upon the actual amount of variation from the 

 true meridian, at the time of survey. 



"With the view of aiding this study, and to place a class of facts 

 upon this subject within reach of those interested in it, I have col- 

 lected a number of records never before published, from surveys and 

 observations made a little before the beginning of this century, and 

 will here present them, with such prefatory remarks as the data 

 allows. 



Castorland Survey. 1794. 



The "Castorland Tract," owned by a Parisian company, and 

 coupled with a romantic but abortive scheme of settlement with 

 common interests, was located on the east and north sides of Black 

 River, in Lewis and Jefferson counties. It was surveyed in 1794-6, 

 and in the beginning, under the direction of Pierre Pharoux, a com- 

 petent engineer and practical astronomer, who perished by being 

 carried over the falls of the Black River, in the present city of 

 "Watertown, in September, 1795. In the journal of this survey the 

 necessity of running lines of lots by the true meridian, is strongly 

 urged, on account of the uncertainty of the compass, from secular 

 variations and local attractions. In their discussions with the pro- 

 prietors this point is insisted upon, but was never carried out. Two 

 valuable observations made by Pharoux deserve permanent record. 

 The first was made at the house of Baron Steuben, in Herkimer, now 

 Oneida Co., June 16th, 1794. The latitude was found by astronomi- 

 cal observations, carefully verified, to be 43° 16'; and the variation, 

 as given by three different instruments, was 3° 58' west. The second 

 was made a mile and a half below the head of the " Long Falls," 

 now Carthage, Jefferson Co., August 5th-13th, 1794, at a locality 

 then named, and often afterwards mentioned, as " Meridian Rock." 

 The latitude was ascertained to be 44° 9' 26", and the variation, by 



