181 



from circumstances connected with the chronometers of the Doro- 

 thea and Trent, during the late voyage to the North Pole, the author 

 is induced to refer these alterations to other causes : he found that in 

 all cases the gaining rates were increased and their losing ones di- 

 minished on ship-board. That this acceleration does not arise from 

 the ship's motion, was shown by its occurrence when the Dorothea 

 and Trent were beset with ice, and when they were at anchor close 

 in shore without any perceptible motion ; nor does it appear that 

 change of temperature was at any time the cause of this change of 

 rates. That the iron in ships becomes magnetic is shown by its 

 polarity, the whole forming, as it were, a large magnet, having its 

 south pole on deck and its north pole below. The inner rim of the 

 balance of chronometers, which is made of steel, will, therefore, be 

 liable to magnetic action, which will be sufficient to cause a very 

 sensible alteration in their rate of going. 



Mr. Fisher concludes this communication with some account of 

 experiments on the action of magnets upon chronometers placed in 

 various positions with respect to their balances, by which it appears 

 that an acceleration in these cases always ensues. It also appears 

 probable, he observes, that the force of the balance spring is affected 

 by the same cause, since chronometers in which they are made of 

 gold, though more difficult to adjust, keep better rates at sea than 

 others. 



An appendix, containing tables of rates furnished by Mr. Coleman, 

 is annexed to this paper. 



An Account of a New Mode of performing the High Operation for the 

 Stone. By Sir Everard Home, Bart. V.P.R.S. Read June 15, 

 1820. [Phil. Trans. 1820, p. 209.] 



The method of removing a stone from the bladder, which is de- 

 tailed in this communication, is as follows : An incision is made in 

 the direction of the linea alba, beginning at the pubes, and four 

 inches long, down to the tendon. The linea alba is then pierced 

 close to the pubes, and divided to the extent of three inches. A 

 silver catheter is now passed into the bladder ; and its point being 

 felt through the wound in the fundus of the bladder, a stilet is 

 forced through it, followed by the end of the catheter. The stilet is 

 then withdrawn, and the opening through the fundus of the bladder 

 enlarged towards the pubes by a probe-pointed bistoury. The ca- 

 theter is then withdrawn, and the stone removed. A flexible gum 

 catheter is lastly introduced, by which the urine passes off. The 

 subject of the above operation was a lad sixteen years of age. In 

 ten days the wound of the bladder healed, and he made water freely 

 by the urethra. The stone was very rough, and about an ounce in 

 weight. 



K -2 



