Illuminating Church Clocks, 



295 



The hour-wheel h, which makes two revolutions in the twenty- 

 four hours, having 48 teeth acting into the large wheel W W, 

 it consequently revolves once in the same period in a direc- 

 tion from left to right. When the pin D arrives at the in- 

 clined part of the right hand lever /, it moves it into the po- 

 sition represented by the dotted line marked /' (accented) when 

 its further progress is stopped by a pin fixed to the frame A B. 



Fig. 2. 

 \ 



B 

 P 



This motion turns the stop-cock C, and lowers the gas at the 

 burners to a small blue flame, which is done at sunrise. The 

 pin D, which has just acted, is placed on the inner side of the 

 wheel W W, as is also the right hand lever I, Suppose the 

 other pin to be at the position indicated by the lower W, and 

 moving up to left hand lever H (accented), it will then be moved 

 into the position shewn at the extreme left. As the day 

 lengthens, the pins are gradually removed from each other, to 

 allow them to act at shorter intervals, and brought nearer as 

 darkness increases. Thus, on the longest day, the pins are 

 at their maximum distance, so that the interval between their 

 acting is only three hours ; while, on the shortest day, they 

 are at their minimum, and the interval is sixteen hours. The 

 altering of these pins gives very little trouble, as one has only 

 to be changed to the next hole every fortnight. 



The friction is so very small, that an ounce weight placed 



