XXXIV 
FIFTH REPORT— 1835. 
The direction of the wind, and the height of the barometer 
and thermometer. 
The direction and velocity of the stream of flow and ebb. 
At what hour (with respect to the time of high-water and 
low-water) the slack-water after the stream of flood, and after 
the stream of ebb, respectively occur. 
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 found again at a future time. The observer ought to 
state the manner in which the height was measured; the man¬ 
ner in which the moment of high-water was fixed upon; the 
time employed, whether apparent or mean solar time , and how 
it was obtained. 
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. Machines 
to dispense with this minute attention are described in the 
Philosophical Transactions , 1831, and in the Nautical Maga¬ 
zine for October, 1832*. 
The uncertainty occasioned by waves may be avoided by 
making the observation in a chamber, to which the water has 
access by a small opening, or by fixing in the water an upright 
tube (of wood or iron, for instance), the bottom or sides of the 
tube being perforated ; in either case an upright measuring rod, 
carefully graduated, and connected to a float, will rise and fall 
with the tide, and permit, at any moment, the height of the 
water to be read off against the collar through which it works. 
This rod may be so constructed as to leave a moveable index at 
the highest and lowest points. 
A long series of continued observations can alone be of use 
towards the determination of the dependence of the time, height, 
and other circumstances of high- and low-water upon the places 
and distances of the sun and moon; but a smaller number of 
observations will often be sufficient to determine the establish - 
ment of any place, with more or less accuracy, according to the 
number of observations ; and the best mode of doing this is by 
comparative observations with some place of which the establish¬ 
ment is accurately known, or where observations are continually 
carried on. A few sets of comparative observations of neigh¬ 
bouring places will give the relative time of high-water at these 
places with considerable accuracy; and thus the motion of the 
tide-wave and the arrangement of the cotidal lines , (or lines 
* Tide-gauges may be seen in operation at St. Katharine’s Docks, London. 
An excellent one has lately been set up near Bristol bv the Literary and Phi¬ 
losophical Institution of that city. 
