82 



LONGITUDE OF KINGSTON. 



[1854. 



and without reflection as to the results ; and he was of opinion 

 Ihat accidents of this description seldom, if ever, occur. This 

 lucid explanation of the theory will, we trust, prove a salutary 

 precaution to proprietors not to confide such dangerous engines 

 of destruction to ignorant and incompetent workmen, for whose 

 acts and incapacity they are, according to the law as laid down 

 in the House of Lords, referred to in our last week's Journal, 

 most clearly responsible. 



Applying this theory to the facts of the present lamentable 

 case, Mr. Fairbairn came to the conclusion that such a boiler 

 as that of Mr. Williamson's ought not to be worked with a 

 pressure much above 401bs. to the square foot, and certainly 

 not exceeding 501bs. It was difficult in this case, from the 

 deficiency of the evidence, to ascertain the exact pressure ; but, 

 from the weights which had been placed upon the valves, it 

 was necessarily excessive. In the course of his examination, 

 Mr. Fairbairn further stated, that mercurial guages could not 

 always be relied on, and were not in every instance correct in- 

 dicators of pressure. He illustrated this by observing, that in 

 the experiments, to which we subsequently refer, he had used 

 two such guages, and found a difference of lOlbs. between the 

 pressure they severally indicated, with which, being of course 

 dissatisfied, he Tras obliged to get columns of mercury, so as to 

 check them, and bring them to a standard. 



In answer to a question whether he conceived that one of 

 the two valves ought to be out of the control of the engineer — 

 whether, in fact there should be an inside valve, or one weighted 

 from the inside, Mr. Fairbairn replied that he had been once 

 favourable to the use of lock-up valves, because he thought 

 that they could not be tampered with. He declared, however, 

 that he since had reason to change his opinion, and he now 

 believed that valves completely exposed were the safer, -either 

 having a dead weight on them, or with levers in front, so that 

 any person could see them. He once had valves on the top of 

 the boiler, so cased up with a hood over them, that although 

 the steam could escape through something like a Venetian 

 blind, not even a stick or a piece of wire could be put through 

 to tamper with the fittings. There was a pulley lever through 

 the stuiBng-box, by which the engineers were able to lift the 

 valve, and there was plenty of room for everything to work 

 freely. On board the navy steamers, they use the lock-up 

 valves; but it is the duty of the chief engineer to report daily 

 as to the state of the valves, as regularly as the log of the vessel 

 is kept. Mr. Fairbairn was pressed to say whether he con- 

 sidered it an advantage to have a valve locked up, or weighted 

 from the inside of the boiler; to which he replied, that it was 

 a difficult question to deal with, but that he had already given 

 his opinion. 



Mr. Fairbairn also submitted the following tabular results 

 of some experiments which he had made in order to ascertain 

 the force which steam acquires in a comparatively short period 

 of time when the engine is at rest, and the usual outlets for 

 3scape are closed : — 



Time in minutes. Pressure in lbs. Temp. Degrees. Volume. 



11-75 24300 980 



1 14-15 246-75 906 



2 16-35 25100 846 



3 19-25 255-25 782 



4 22-35 259-75 720 



5 25.75 264-00 665 



6 28-95 268-37 621 



7 32-15 273-00 582 



8 35-75 277-00 545 - 



9 39-95 282-00 506 



10 44-25 286-37 472 



Time in minutes. 



11 



12 



13 



14 



15 



16 



17 



18 



19 



20 



21 



I*ressure in lbs. Temp. Degrees. Volume. 



.. 48-35 291-00 445 



.. 52-75 •... 295-37 418 



.. 57-75 .300-00 392 



.. 03-75 304-25 365 



.. 68-95 308-75 344 



.. 74-75 313-00 324 



.. 80-35 317-75 306 



,. 87-25 322-00 288 



.. 93-95 326-12 273 



,. 101-15 331-00 257 



,. 108-75 335-62 243 



22 112-00 ..■ 3.37-00 This experiment lost. 



These experiments were made with a boiler prepared for the 

 purpose; and it will be seen that the steam which was starting 

 ll-751bs. on the square inch, increased in density to nearly 

 four times the pressure, and in 10 minutes more it was nearly 

 nine times; that it continued to increase in an accelerated 

 ratio, until in loss than 20 minutes, had he been able to con- 

 tinue the pressure, it would have reached a point beyond all 

 powers of resistance, when explosion must have been the result. 

 — Mining Journal. 



Longitude of Kingston, 



To the Editor of the Canadian Journal. 



Sir, — The Longitude of Kingston is sometimes stated to be 

 76° 40'. This, however, differs considerably from the truth, 

 as might be expected from the comparatively rough and hasty 

 manner in which the portions of the principal points in a newly 

 settled country must, in general, be first determined. Eclipses 

 of the sun, it is well known, afford one of the most accurate 

 means of determining the longitude, independently of such 

 means as telegraphic communication with an Obsei-vatory, the 

 Longitude of which has been already ascertained. The Longi- 

 tude of Kingston, as deduced from two Eclipses of the Sun, 

 and one Transit of Mercury ; the time being taken from a care- 

 fully regulated clock, the pendulum having a wooden rod, is as 

 follows :— 



By Eclipse of Sun. Longitude W. 



April 25th, 1845 76° 32' 45". 



May 26th, 1854 76° 32' 59". 



By Transit of Mercui-y. 



May 8th, 1845 76° 31' 45". 



Another Eclipse, May 6th, 1845, the time being taken 

 from a carefully regulated watch, gave 76° 31'. The mean of 

 these observations, 76° 32' 7-25" W., may, therefore, be con- 

 sidered as the Longitude of Kingston, very nearly. A lunar 

 distance, worked out from observations with two insti-uments 

 only, and which may be rejected except as an approximation, 

 gave 76° 30'. The mean longitude, deduced from twelve ob- 

 servations of immersions, and emersions of Jupiter's satellites, 

 a comparatively imperfect mode of its determination, gives 

 76° 31' 17". 



Those who are familiar with such questions are aware that, 

 until a regular Observatory for astronomical purposes be estab- 

 lished, there must, even afler very careful observations, be 

 some uncertainty at least in the determination of the longitude. 

 But the limit of error in the above mean of 76° 32' 7-25" W. 

 is, in all probability, not more than from a third to a half of 

 a statute mile. 



I do not know how far the Longitude and Latitude of To- 

 ronto may be considered as ascertained. 



I am. Sir, your very obedient servant. 



James Williamson. 



