PROCEEDINGS FOR 1897 XV 



use of the ordinary tyj^e of instrument. The essential point is to have a 

 driving clock which can be readily detached from the rest of the instru- 

 ment. This is secured by placing the driving clock inside of the revolv- 

 ing cj'^linder which carries the sheet of paper on which the tidal record is 

 marked, as is done in some types of self-registering insti'uments of smaller 

 size used for meteorological pui-poses. In case of failure of the clock, a 

 duplicate cylinder with clock inside can be substituted in one or two 

 minutes, as it is released by a single screw. The defective clock can then 

 be sent away for repairs without interruption to the record. This new 

 form of instrument is also provided with interchangeable gearing, by 

 which any one of four scales can be used, corresponding to a range in the 

 tide of 9 feet, 18 feet, 27 feet, or 36 feet. Our tides have such a variety 

 in their range that when an instrument requires to be changed to a new 

 position, it has usually been first necessary to return it to the makers in 

 Britain to have the gearing altered to another scale. There are also 

 several minor improvements, especially in so arranging the carriage of 

 the marking pencil that the point of the pencil is readily accessible. 

 This is important in making the comparisons on which the datum 

 depends, to which the observations have ultimately to be reduced. A 

 recording instrument of this new type, manufactured by Messrs. A. 

 Tiégé & Co., London, has been in use at Pictou during last season with 

 very satisfactory results. This type of instrument will be substituted for 

 those now in use at the more isolated stations. 



Tide Tables arid Tidal Differences. 



The improvement which can be made in the tide tables each year 

 has to depend upon the balance remaining out of the small vote available 

 for this survey after the charges of first importance are met. 



The tide tables for Quebec for 1897 were accordingly calculated from 

 the same data as before, namely, one full year's record. These are now 

 accompanied by tidal difterences for the whole tidal portion of the St. 

 Lawrence waterway from Three Eivers to Gaspé, a distance of 450 miles. 

 The basis of the tide tables for Halifax has been extended to include the 

 four years for which record was found to exist, namely, 1851, 1852, 1860 

 and 1861. At the request of the Pilot Service tide tables for Father 

 Point, the St. Lawrence pilot station, have been prepared for the present 

 season of navigation. To save the expense of jirinting, these are in 

 manuscript only, and are posted at the lighthouse at Father Point. In 

 the St. Lawrence above Quebec special tide tables have been prepared for 

 St. Croix Bar, which is at present the shallowest point in the river, until 

 the deep channel-way is completed. Provisional tide tables have also 

 been prepared for Charlottetown and Pictou in time for the present 

 season of navigation, based upon the observations of the previous season, 

 already referred to. These observations showed that the tidal station to 



