ON TIME MEASURERS. 345 



paper which they have read on the compensation of pendulums I 

 will not deal with. A few years ago it would have been vastly 

 more interesting to scientific men than it is now, inasmuch as elec- 

 tricity is now the means of taking the exact time to all the large 

 cities, and electric clocks have to a great extent taken the place of 

 the accurate pendulum which we used to have so many experiments 

 upon. The very ingenious contrivance of the Astronomer Royal, 

 shown on the clock of the Messrs. Dent, and referred to in the paper 

 just read, for correcting the influence of the atmospheric pressure on 

 the pendulum, known as the barometric error, is. in the opinion of so 

 high an authority as Sir Edmund Beckett, unnecessary. He tells us 

 that when testing the Westminster clock for the barometric error, he 

 found it had none ; which he attributed to the rather unusual length 

 of the arc, or swing of the pendulum, and after careful experiments, he 

 found that this error of the pendulum could always be corrected by 

 regulating the length of arc. But as chronometers and pocket watches 

 have become vastly more important to the general public than they used 

 to be, I will say a few words upon chronometer balances, and those of 

 pocket watches. There are a variety of balances which may be seen 

 down stairs lent by the Horological Institute, and I am sorry they are 

 not properly displayed or catalogued. There are amongst these balances 

 specimens of various inventions, from the first made by Arnold and 

 Earnshaw to the latest sent for trial to Greenwich, and it is curious to 

 note how very little difference there is between the earliest and latest 

 examples, and not encouraging to see how little improvement has been 

 made during the seventy years that have elapsed since the invention 

 of Earnshaw : although there are in this collection alone some forty 

 differently constructed balances, all being the results of attempts to 

 improve upon it. 



There is also a collection of balances shown by Messrs. Dent, most 

 of them being a modification of the form, known in the trade as " Dent's 

 Balances," and others exhibited of very complicated construction, but 

 after much time and trouble spent on these ingenious contrivances, it 

 has been found that simplicity of form is indispensable to a reliable 

 timekeeper, and the balance of Earnshaw without modification is what 

 is all but universally used for ship's chronometers at the present time. 

 So also is it with the pocket watch, although the manipulative skill oC 



