192 
SECOND REPORT- 1832. 
The height of high water appears to vary very little at different 
months of the year. The difference between spring and neap 
tides at the London Docks is about 3 feet, and the rise about 
19 feet. Mr. Dessiou has undertaken the laborious task of 
discussing 6000 observations more, in addition to those of which 
the results are given in the Philosophical Transactions , in order 
to obtain with greater accuracy the corrections due to changes 
in the moon’s parallax and declination. 
As the times and heights of high water at London Bridge 
are in future to be inserted in the Nautical Almanac , and as 
Tables for the prediction of these phenomena are to be given 
in the new edition of the Requisite Tables, we may hope short¬ 
ly to see this question rescued from the neglect in which it has 
lain so long and so undeservedly. With this view it is of great 
importance that observations should be originated in various 
parts of the world, and with greater attention to accuracy than 
any which are yet carried on, except perhaps those at Brest, 
which were instituted by the French Government in 1806, at 
the request of Laplace, and have been continued ever since. 
In August last year, at the request of the Council of the Royal 
Society, directions were sent from the Admiralty to the masters 
attendant at Woolwich, Sheerness, Portsmouth and Plymouth, 
to cause observations of the Tides to be made, and to forward 
reports quarterly. This order has been complied with, and 
the observations are in the possession of the Royal Society. 
I have not been able to ascertain that any observations are 
made on the coast of Scotland and Ireland; and in this country, 
with the exceptions I have noted, and at Liverpool, these in¬ 
teresting phenomena pass away unheeded and unrecorded. I 
trust that the influence of the British Association will be ex¬ 
erted to remove in some degree this national reproach. 
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 thermometer should be noted, and the direction and velocity 
of the current should also be described. 
The circumstances of high w r ater are more interesting, and 
admit generally 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 
* 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. 
