230 On the I/liimiiia/iuii of the Dial 



to disengage a catch that holds up the hand of the main stop- 

 cock, so that by this means the clock shuts ofF the gas in the 

 morning. A painted board with the respective months and 

 hours serves to direct the person who has the charge of it, to 

 shift the arm as the season alters. The pipe afterwards ascends 

 and branches off to the respective dials. 



The lamp is formed of a copper bowl, eighteen inches diame- 

 ter, and of a parabolic figure, of three inches and a half focus : 

 it is lined in the inside with small pieces of looking-glass, im- 

 bedded in white paint and putty, similar to some of the reflectors 

 used for light-houses; the front is enclosed with glass. The 

 burner used is a No. 3, Argand, with each alternate hole shut 

 up, and equal to a No. 1, Glasgow Argand. 



The lamp, properly inclined so as to illuminate the dial, 

 is suspended about seven feet from the building, above the 

 centre of the dial, the bottom of the lamp is on a line with the 

 top of the dial plate. From the situation of the dial it was 

 necessary to fix the lamp from the balcony ; and that it might 

 be easily got at, the branch is jointed so that it can be drawn 

 up to the person within the rail, to be cleaned when neces- 

 sary. It is lighted from the inside of the steeple by z. flash pipe, 

 or separate tube, pierced along one of its sides with holes, and 

 partially covered to protect it from the weather ; so that when 

 the gas is admitted and a light applied at one end, each hole 

 lights the next till the flame reaches the farthest extremity, and 

 thus kindles the gas issuing from the burner; the flash pipe is 

 then shut. The exterior of the lamp represents the Eagle of 

 Jupiter armed with lightning, and the whole is surmounted with 

 the city arms. From the cheerful appearance of this dial, it is 

 likely that other clocks may likewise be lighted, where the build- 

 ing will admit : a simpler and neater method than that which the 

 peculiarities of the Tron church steeple rendered necessary, 

 might be adopted ; namely, to cut a small circular window 

 about two feet in diameter above the dial, from which the lamp 

 might be put up and cleaned when necessary, and when lighted 

 pushed forward : here a straight rod only would be required to 

 suspend it, which might be run out over a wheel having a balance 

 weight in the inside to return it again to the window in the morn- 



