142 Gas-light hi the Tron Steeple of Glasgow 



The lamp is lighted every afternoon a few minutes be- 

 fore sun-set and at day-light the next morning it is extin- 

 guished by the machinery of the clock as represented in 



figure 3. 



G is the main pipe by which gas is supplied to the lamp, 



C is the stop cock, opened and shut by the lever B, at 

 present open. 



D is a wheel upon the spindle of the hour hand of the 

 clock, making two revolutions in twenty four hours, 



E a wheel moved by the other of double the diameter, 

 and of course making one revolution in the same time. 



H the beam of wood which supports these. ' 



Upon the wheel E is a moveable index F, which is set 

 about once a month, to correspond with the sun's rising- 

 As the wheel revolves, a projecting knob at the end of this 

 index, gradually reaches the upper end of the lever A, and 

 presses it forward ; this by moving disengages the lever of 

 the stop cock B, which dropping downward by its own 

 weight, falls into the position marked by the dotted lines I, 

 and cutting off the supply of gas extinguishes the flame. 



This plan of lighting steeples w^as the fruit of the joint la- 

 bours of Messrs. J. & A. Harts and Mr, A. LiddelL The 

 Messrs. Harts are operative bakers in Glasgow, who have 

 distinguished themselves by their scientific attainments. Mr. 

 Liddell is an ironmonger and his professional knowledge 

 was found useful in the practical application of the plan. 

 Messrs. Harts are found in their bake-house during the great- 

 er part of the day and their leisure hours are devoted to 

 scientific and mechanical studies. They made the Camera 

 Obscura in Glasgow Observatory, one of the largest in the -- 



kingdom, the speculum (a metallic one similar to those in 

 Herschel's large Telescopes) about twelve inches in diame- 

 ter, and the lens nearly as large were wholly prepared by 

 themselves. They have in their bake-house a working 

 model of the steam engine, (one of several, which they have 

 constructedj) on a new plan which drives a turning lathe in j 



the apartment above, and they have constructed a very su- 

 perioi reflecting telescope six feet in length. Lately they 

 have made some curious discoveries m the art of staining 

 glass. Their scientific knowledge is unaccompanied by the 

 slightest degree of pride or ostentation, and they continue to 

 labour as diligently at their trade as if they knew no higher- 

 pleasure. 



