284 Admiral Krusenstern on Mr. Barlow's Method 



Admiral Count Heyden, an officer of high scientific attain- 

 ments, and equally interested with me to learn the results of 

 these observations. M. Chalizoff, a master in the navy, went 

 with us, who had been already employed by Count Heyden 

 when commanding at Sweaborg to make observations on the 

 deviation of the compass. The governor of Cronstadt, Ad- 

 miral Moller, brother to the minister of marine, gave imme- 

 diately on our arrival an order to the commander of the Oly- 

 nip, a brig of war mounting twenty twenty-four pounders, to 

 warp the ship according to my directions, and at 4 o'clock the 

 next morning we commenced our experiments, of which I 

 shall give you as detailed an account as possible, requesting 

 you to communicate such remarks as you may find requisite 

 to make on them. Not having a theodolite to observe the 

 bearings of the ship from shore, we compared the compasses 

 we had to make use of, and found a difference, between the 

 Gilbert compass and the azimuth compass belonging to the 

 ship, of three-fourths of a degree, which difference has always 

 been applied. The brig being very high fore and aft, it was 

 very difficult to place the stand of the compass conveniently for 

 the observer : at length we placed it in the after part of the ship 

 on the starboard side on the top of a small cabin*. It was 

 equally difficult to fix upon a spot on shore to take the bear- 

 ings, from the Roads of Cronstadt being every where surround- 

 ed by large batteries, where on account of the guns the ob- 

 servations could not be made. The only spot that could be 

 selected was the end of a bridge opposite to the ship, at the 

 distance of about half a mile. M. Chalizoff, a very expert and 

 careful observer, was sent on shore with the ship's azimuth 

 compass, while Count Heyden and myself remained on board. 

 The ship was now warped round the compass to every point, 

 and sometimes to less, as you will perceive by the original ob- 

 servations which I herewith inclose. As soon as the ship was 

 swung and steadied, a signal flag was hoisted on board, and 

 repeated on shore ; then both observers keeping the two flags 

 on board and on shore in the same line of sights, three bear- 



* It is to be regretted that it was necessary to place the compass in this 

 situation, because, being elevated and further aft than tLc jsual place, there 

 is no doubt the errors observed were much less than they would have been 

 in the natural situation for the azimuth. In all probability they would 

 have been increased from a half to at least three quarters of a point, or 

 7° or 8°. 



The difficulty here noticed, of not being able to see the shore station from 

 the ship, has occurred in some English vessels where the bulwarks have been 

 very high, and in vessels with poops. The best way in these cases is for the 

 two observers (instead of taking each other's bearing) both to take the bear- 

 ing of the sun by signal at the same instant, then the difference in these 

 bearings will be the local attraction. — P. B. 



ings 



