414 EEPOET — 1892. 



is one wMcli, thougli adopting the same principle, is very different in 

 appearance and deserves a special mention. This is the ' Cyclometer ' 

 of Mr. Ransome (manufactured by Messrs. Manlove, Alliott, & Co., of 

 Nottingham), which gives the time of rotation of any shaft to the ^tyW^^ 

 part of a second; and not only is the total time of each revelation re- 

 • corded, but also the time taken in turning through any minute angle or 

 portion of a revolution may be obtained with equal accuracy. The prin- 

 ciple upon which this speed-recorder works is very simple. A cylinder 

 covered tightly with smoked paper is attached to the end of the shaft 

 whose speed it is required to measure. On one side of this drum is 

 placed a tuning-fork of known pitch ; one of the arms of the fork carries 

 a small style, which (when the fork is vibrating) oscillates in a line at 

 right angles to the direction of rotation of the drum. When at work the 

 tip of this style lightly touches the smoked paper on the revolving drnm, 

 and records on it the number of vibrations which the tuning-fork makes 

 whilst in contact with the paper. It is well known that each vibration 

 must be made in an equal interval of time, the amount of which is known 

 from the pitch of the fork. Thus the time taken in seconds for a point 

 on the smoked paper to traverse one inch will be the number of waves in 

 that inch divided by the number of vibrations per second corresponding 

 to the pitch of the fork used. After the record has been taken the paper 

 is removed from the drum, and the marks are rendered permanent by any 

 thin varnish. The slope of the waves will be a measure of the speed of 

 the drum, but it is easier in this case to count the number of vibrations 

 in a given space. 



Under this head is a railway-speed time-recorder used in America. 

 The object of this instrument is to indicate, not only the speed of the 

 train when it is I'unning, but the time at which the train stops, how long 

 it remains still, and the speed at which it has run. The work is recorded 

 upon the paper ribbon, which is divided into minutes and hours, and is 

 put in motion by a train of mechanism controlled by an eight-day time 

 movement, to which it is attached. The motion of the car sets in action a 

 train of gearing, which in turn gives motion to the pencil mechanism, 

 which traverses crosswise of the paper, while the paper itself traverses 

 lengthwise at a uniform speed. The pencil mechanism is put in motion 

 by an eccentric placed upon the axle of the car. A straight line length- 

 wise on the paper ribbon denotes a stop of the train. The pencil crosses 

 the paper every half-mile the car travels, and from one side of the paper 

 and back again indicates a mile ; every fifth mile the pencil travels 

 farther, so as to make the line higher, in order that the miles may be 

 counted up with more convenience, and the work done located with 

 greater ease. This record can be continued for any number of days, the 

 capacity of the machinery and the paper ribbon being sufficient to record 

 eight or nine days by one winding. This ribbon, it will be seen, records 

 the time of reaching and leaving each station, and every part of the 

 work done. 



e. Instruments for obtaining an autographic record of the rise and 

 fall of temperature are employed at Kew and other observatories, the 

 level of liquid in the thermometer being continuously photographed. 

 But within the last few years very much more convenient self-recording 

 thermometers have been invented. MM. Richard have designed an in- 

 strument of this kind, which consists of a curved brass tube, of rather flat 

 section, hermetically sealed, filled with an expanding liquid. The tube is 



