130 Reviews, and Notices respecting New Books. 



on the construction of Tide Tables for predicting the time and height 

 of h'gh water at any port ; in which the author notices the results he 

 has himself obtained by discussing the observations made at the Lon- 

 don Docks. In A uguSt 1 83 1 , we find that, at the request of the Coun- 

 cil of the Royal Society, directions were sent from the Admiralty to 

 the master attendants at Woolwich, Sheerness, Portsmouth, and Ply- 

 mouth, to cause observations of the Tides to be made, and to forward 

 reports quarterly. The observations which have accordingly been 

 made are in the possession of the Royal Society ; but Mr. Lubbock 

 remarks, " I have not been able to ascertain that any observations 

 are made on the coast of Scotland and in this country, with the ex- 

 ceptions I have noted; and at Liverpool these interesting pheenomena 

 pass away unheeded and unrecorded. I trust that the influence of 

 the British Association will be exerted to remove in some degree this 

 national reproach." 



A valuable set of instructions for making and recording observa- 

 tions of the tides are next given; and these, deeming them of the 

 utmost importance to the progress of this most interesting branch of 

 science, we transfer entire to our pages ; at the same time earnestly 

 requesting such of our correspondents or readers as may possess 

 suitable opportunities, to institute, or cause to be instituted, regular 

 observations agreeably to those instructions. 



" Observations of the Tides should record particularly, 



" The time and height of high water. 



" The time and height of low water. 



"The direction of the wind and the height of the barometer and thermo- 

 meter should be noted, and the direction and velocity of the current should 

 also be described. 



" The circumstances of high water are more interesting, and admit gene- 

 rally of more accurate observation, than those of low water. 



" The height of the water must be given from some fixed mark or line*, 

 which should be described accurately, so that it may be easily recovered. It 

 should also be carefully stated whether the time in which the observations 

 are given is mean or apparent, and how obtained. 



" The name of the observer, or his initials, should be attached to each ob- 

 servation. The simplest method of observation appears to me by means of 

 a staff, carefully graduated, connected with a float, and working through a 

 collar where the height is read off. The staff must be kept in a vertical po- 

 sition by means of friction rollers ; the float should be in a chamber to which 

 the water has access by a small opening, in order that the ripple may be as 

 much diminished as possible. It would be convenient to have a clock close 

 to the tide gauge ; and if made to strike minutes, so much the better. The 

 observer should note the height of the water at the end of every minute, for 

 half an hour before the expected time of high water, and until there can be 

 no doubt that the time of high water is past. The minute at which the water 

 stood the highest, or the time of high water, is then easily seen. This pro- 

 cess is tedious, and it might be imagined that it would suffice to note the 

 time when the water reaches a certain height shortly before high water, and 

 the time when it reaches the same line in its descent; but the water rises 



* '* I consider this of particular importance, and I allude to it because it 

 has not been complied with in some observations transmitted to the Royal 

 Society. Observations of the rise are useless." 



