Performance of Some Timekeepers. 185 



In referring to the above list of watches, it may be men- 

 tioned, that a, b, c, d, e, and / were specially selected and 

 adjusted by the makers for exhibition and competitive trial, 

 the others were purchased from ordinary stock. The marine 

 chronometer is a very fine one by George Timewell, of Liver- 

 pool, which lias not been cleaned for four years, and the 

 astronomical clock is the celebrated Frodsham 991, which, 

 when its rates were examined by the horological jury of the 

 Paris exhibition of 1867, was pronounced to be one of the 

 best in existence, its rates are found by celestial observations, 

 generally taken every second or third day. Those given in 

 the above list extend from near the beginning of February 

 to the end of August in the present year, they, therefore, 

 include the hottest and coldest periods, the gradual change 

 of rate is owing to the clock being slightly under compensated. 

 The iron jar containing the quicksilver is only 8 J inches long 

 inside; this has proved to be not quite enough. The rates of 

 the watches and chronometer have been determined by means 

 of daily comparisons with the standard mean time clock of 

 the observatory, they have all been obtained from trials 

 made during the last few months, with the exception of 

 watch g, whose rates are given for November and December 

 1879, as I have not often worn it since. All the errors of 

 position have been determined since the beginning of last 

 year. It should be stated also that the rates of the astrono- 

 mical clock have been corrected for the variations of atmo- 

 spheric pressure, as it has been found for this particular 

 clock, that a rise of one inch of the barometer causes it to 

 lose half a second per diem. 



On examining the above table of rates, it will be seen at 

 once to what enormous dimensions the error of position 

 sometimes attains ; in watch m, the English machine-made 

 watch, it amounts to a daily difference of eight minutes and 

 forty-six seconds between pendant right and pendant left; 

 while in the Waltham, costing the same money, and also a 

 machine-made watch, the greatest difference is only nineteen 

 seconds. Again, in w r atch j, a finely-finished London fusee 

 watch, the error reaches two minutes forty-five seconds a 

 day. Comparing these with the two high-class expensive 

 London watches b and d, whose largest errors of position are 

 only somewhat over five seconds, it shows what English 

 watchmakers can do when they are well paid for their work; 

 their ordinary watches, however, are very badly adjusted, 

 and if they do not improve in this particular, they are likely 



