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which at the beginning of a voyage attracted the North end of the 

 needle, should it become magnetic, would repel the North end, under 

 certain obvious conditions. 



I believe it was recently discovered that the needle was influenced 

 to a dangerous extent on a Man-of-war by the side arms of a sentry 

 who passed near the compass and whose bayonet had become magnet- 

 ised by having been stored near the ship's dynamo. 



All of these irregularities of the needle may be successfully guarded 

 against in fair weather, by frequent astronomic observations, but such 

 observations require special instruments, which are not always obtainable. 



In the absence of astronomic observations, the correctness of the 

 work in hand depends upon the skill of the observer and his knowledge 

 of the capricious pranks, so to speak, of this little instrument, which, 

 with all its faults, is so marvelously useful. 



With a view to increase the accuracy of compass surveys, I several 

 years ago, invented and obtained a patent, in the United States, upon a 

 little instrument which I called an Improvement on Transit Compasses, 

 and it obtained considerable favor among surveyors : in fact, some of 

 my confreres were kind enough to say that they thought that my 

 instrument would supercede the plain sight compass. 



The instrument consists mainly of a compass, rigidly attached to 

 the upper side of a telescope turning npon trunions in a bifurcated 

 holder. It possesses many of the advantages of the heavy and expensive 

 transit instrument, with the lightness and inexpensiveness of the compass, 

 and it is therefore particularly desirable for surveys in places not easily 

 accessible. 



In ordinary so-called "line running" the surveyor would only use 

 the needle at starting, after which required points in the great circle 

 would be accurately determined by the use of the telescope, indicated 

 in the cut of the instrument. 



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