418 REPORT— 1892. 



1. The mean lunar semi-diurnal. 



2. The mean solar semi-diurnal. 



3. The larger elliptic semi-diurnal. 



4. The luni-solar diurnal declinational. 



5. The luni-diurnal declinational. 



6. The luni-solar semi-diurnal declinational. 



7. The smaller elliptic semi-diurnal. 



8. The solar diurnal declinational. 



9. Tlie lunar quarter diurnal, or first shallow- water overtide of mean 



lunar semi-diurnal. 

 10. The luni-solar quarter diurnal shallow- water tide. 



It has a hanging weight, consisting of an ink-bottle, with a glass 

 tubular pen which marks the tide level in a continuous curve on a long 

 band of paper, moved horizontally across the line of motion of the pen 

 by a vertical cylinder geared to the revolving shafts of the machine. 



An instrument of a similar kind was afterwards constructed by Mr. 

 Roberts for the India Office, and it was estimated that, by moving the 

 handle up and down through the range of a semi-diurnal tide in two 

 seconds, a year's curve could be produced in twentj'-four minutes. But 

 this is, however, ten times the speed to which the mechanism actually in 

 use limits the practical working of the India Office instrument. Sir 

 W. Thomson has therefore designed a third tide-predicter, which he 

 describes in the above paper, the general principle of which is therein 

 represented in an engraving. 



h. There are a variety of self-recording instruments which are 

 employed for chronographic purposes, such as giving the time of opening 

 the door of a furnace, or of charging a blast furnace, or of the passing of 

 a railway train, or of the period at which a watchman passes a certain 

 point. These are sometimes operated by direct mechanical action, as in 

 the watchmen's clocks invented by Mr. IBailey. One of the best of these 

 is an invention by Mr. F. M. Pratt, described in the ' English Mechanic' 

 These tell-tales are employed for controlling the watchmen of works, 

 hospital nurses, timekeepers of factories, inspectors of police, weighing- 

 machine men, gaswork stokers, stablemen (that it may be seen what 

 time the stable had been opened), domestic servants (to ascertain what 

 time they got up), fire brigades (to see what time the alarm-bell was 

 rung), scavenging superintendents, bank porters, dock warehousemen, 

 prison warders, gatekeepers, &c. 



Mr. Burke has invented a watchman's watch, which is made by Mr. 

 Bailey, and acts upon the principle of a mark being made on a recording 

 drum, to do which a key must be inserted, which can only be obtained at 

 each station which the watchman has to pass. Several different types of 

 recorders in connection with the time and movement of engines in mills 

 and factories are also made by Mr. Bailey. Instruments of this kind are 

 frequently actuated from a distance by means of an electric current. 

 Messrs. Richard Ereres make a controlling chronograph in which an 

 electro-magnet, carrying a pen, traces a continuous line. Every time 

 the process under observation closes the circuit and establishes a current, 

 the pen traces a vertical line, and the dui'ation of the process, as well as 

 the exact moment at which the marks are made, are given by the diagram. 



It will be seen that among the self-recording instruments mentioned 

 ai'e anemometers, barometers, chronographs, hygrometers, dynamometers, 



