^8 Mr. Goldingham's Report [Oct. 



become sufficiently dry, the canvass Observatory may be placed 

 over it, the door fronting the face of the pillar, and the face of 

 tlie pillar about two feet behind the ridge pole ; the whole of the 

 pillar to be nearer the left side of the tent than the right side. 

 The plank should be properly secured, and perpendicular to the 

 horizon. The plank being firm, the clock may be screwed to it, 

 which should be done in the most secure manner. The pendu- 

 lum to be kept every way as at the Observatory, and the works 

 of the clock the same ; the arc for measuring the vibration will 

 be a guide in placing the pendulum, the point of which should 

 stand 1 division to the right of 0, and 0*25 of an inch in front 

 of the arc : by having the face of the pillar upright and flat in 

 the first instance, the plugs so placed in it that the plank shall 

 also be upright and firm against the face of the pillar, the clock 

 will be easily and firmly screwed in the position mentioned. 

 The projecting part of the pillar on which the bottom of the 

 clock-case stands should be perfectly level. The pendulum of 

 the clock is first to be put up, and then the works.''^ If the 

 black paper and disc should have been rubbed off, the ball of 

 the pendulum is to be covered again, and a fresh disc put upon 

 the centre of the ball. The clock should have been going 24 

 hours at least before you begin to ascertain its rate ; get it to as 

 «mall a rate as you can without losing too much time. 



" The frame for supporting the pendulum of experiment may 

 now be secured. At the Observatory, I was obliged to let the 

 back of the frame Scinches in the wall ; the surface of the plugs 

 having been let in beyond the surface of the wall exactly that 

 quantity ; but the clock was then placed against the wall ; here, 

 there will be a plank, which is exactly 2^ inches in thickness, 

 so that the surtace of the plugs should be let in only 1-^ inch, 

 and the front of the pillar, where the frame is to be placed, cut 

 away to that depth. Care should be taken that the frame is 

 put up at first, so that the top of it shall be as nearly level as 

 possible ; and at such an height, that when the small frame with 

 the agates is also put up, the point of the pendulum shall just 

 come to the divisions of the arc for measuring the vibrations ; 

 and also, that the middle of the black slip at the lower part of 

 . the pendulum shall be as nearly as possible opposite the centre 

 of the disc. 



" The large frame being levelled + by the spirit levels, put up 

 the smaller frame containing the agates. Let this be most 

 accurately levelled ; screw up the Ys, and put up the pendulum 

 of experiment, with the knife-edges in the Ys, having first wiped 



• IVIinute written instructions were also furnished for putting up the works and 

 pendulum of the, clock, to make the party independent of assistance in that part of the 

 operations. 



+ Lead is placed between the parts of this frame ; so that with the purchase of the 

 lever, it may be flattened, and the frame thus brought into level ; it should, however, 

 b« made as nearly level as possible by the workmen when putting it up. 



