122 



FEGRETTI AND ZAMBRA, HOLBOKN VIADUCT, E.C., 



A. Dial of clock. 



B. Float-wheel. 



C. Guide for recording 



pencil. 



D. Recording pencil. 



E. Hourly marker on 



datum lines. 



F. Datum lines and 



registering pencil. 



G. Main Drum driven by 



clock. 



H. Eeel of paper. 

 I. Haul-off drum. 

 J. Pendulum of clock. 

 K. Driving weight of 



clock. 

 L. Driving weight of 



haul-off drum. 

 M. Haul- off drum winder. 

 K". Platinum wire to float. 



FIG. 126. 



SIR WM. THOMSON'S TIDE-G-UAGB. 



175. The instrument consists of an astronomical clock, float- wheel and 

 gear work for reducing the scale, and three drums, the whole fitted on a suitable 

 plate and supporting standards, and requiring no further fixing. The clock is 

 fitted with a six- spur gravity escapement and compensated pendulum, and 

 serves to show the time and to drive the centre or main drum of the instru- 

 ment. The float wheel is provided with a right-angled groove in which the 

 platinum wire of the float coils itself during the rising tide. The right-hand 

 drum receives a reel of paper, and the paper is fitted to the instrument without 

 further fixing. The haul-off drum receives the paper records after it has 

 passed round the main drum. The paper may be left to accumulate almost 

 without limit on the haul-off drum, or can be removed at any time. The 

 datum line on the record paper is traced by a fixed pencil, which can be 

 adjusted to any level. Any number of horizontal lines can be ruled in this 

 manner if desired. 



