Performance of Borne Timekeepers. 173 



with a heavy rim, called the balance, at the other end, 

 together with hands and a dial to indicate the revolutions of 

 some of the wheels. If the short hand of a common watch 

 makes two revolutions while the earth is turning once 

 round, as referred to a fictitious regularly-moving sun in the 

 heavens, which is never very far from the real sun, then the 

 watch is said to be keeping exact tiihe. If, however, the 

 watch be required for astronomical work, and to keep what 

 is called sidereal time, then the short hand should make two 

 revolutions while the earth turns once on its axis, as referred 

 to a fixed star. There is, therefore, no difference in the 

 mechanism of a mean-time and sidereal watch ; the latter 

 simply gains 3 mins. 56*55 sees, a day on the former, or one 

 day in a year. In a watch train that part of the mechanism 

 which converts the continuous revolutions of the last, or, as 

 it is called, the scape wheel, into the reciprocating motion of 

 the balance, is called the escapement, and on its construction, 

 as well as that of the regulating spring (which is called the 

 hair or balance spring) and the balance itself, the timing 

 qualities of a watch chiefly depend. 



The oldest form of escapement is that known as the 

 verge or vertical escapement. From the time of the inven- 

 tion of watches till about the commencement of the present 

 century, a period of about two hundred years, it was almost 

 the only escapement used. It is now rarely met with, in 

 Australia at least, except in the form of the old, thick, 

 double-cased watch — the well-known " turnip" as it is some- 

 what irreverently called. I see, however, according to 

 Saunier, that more than 300,000 of watches with verge 

 escapements are annually made in one of the cantons of 

 Switzerland. Very few of these, however, find their way 

 out here. In this escapement the plane of the scape wheel 

 is at right angles to those of the other wheels, so that when 

 the watch is laid flat it stands vertical. Hence the name. 

 This necessitates the watch being of considerable thickness, 

 as well as the use of either bevelled or crown wheels. The 

 principal advantage of the verge escapement seems to be 

 that the impulses are given so directly that the pallets 

 require no oil. It seldom requires cleaning, so that the 

 watch will go with an amount of dirt that would be fatal to 

 the action of most others. Its disadvantages are that the 

 impacts are so severe and so applied as to cause a recoil 

 action of the train. This causes it to wear out rapidly. 

 At the same time it so hampers the free motion of the 



