388 MR. LUBBOCK ON THE TIDES IN THE PORT OF LONDON. 
When the moon passes the meridian at three o’clock, 6 — — X + = 15°. 
log. sin 30° = 9.6989700 log. cos 30° = 9.9375806 
9.5784858 9.5784858 
9.2774558 9 .5160164 = log. -328 1 
log. 1.3281 = .1232308 
9.1542250 = log. tan 8° 7' or 32' 38" in time 
2 6, — = — 32' 38", 6, - \ = 16|', 6 t = l h 25 m — 16 m = l h 9 m 
In this way the following Table was calculated. 
Time of 
Moon’s 
Transit. 
Interval between the Moon’s Transit 
and the Time of High Water. 
Error 
of 
Calculation. 
Observed. 
Calculated. 
h 
h. m. 
h. m. 
m. 
0 
1 57 
1 56 
— i 
1 
1 42 
1 41 
— i 
2 
1 26 
1 25 
— i 
3 
1 11 
1 9 
o 
4 
56 
54 
— 2 
5 
45 
44.1 
- 0.9 
6 
42 
41 
- 0 
7 
52 
53.7 
+ 1.7 
8 
1 23 
1 25 
+ 2 
9 
1 56 
1 56.3 
+ 0.3 
10 
2 10 
2 9 
— 1 
11 
2 8 
2 6.5 
1-5 
According to Table III. the establishment* of the London Docks is l h 57 ni . 
Adding ten minutes, the establishment of London Bridge is 2 1 ‘ 7 m - The esta- 
blishment of the London Docks according to Mr. Bulpit, who has calculated 
the times and heights of high water in the river for many years, is 2 h . 
Mr. Bulpit’s calculations are founded on tables constructed by the late Captain 
Huddart, which have not been published. 
In the Philosophical Transactions, vol. xiii. p. 10, Flamsteed gives “ A 
correct Tide-table, showing the true times of the high waters at London Bridge 
to every day in the year 1683.” It appears from his remarks that the earliest 
Tide-tables which were calculated for the Port of London were made on the 
supposition that the tide always followed three hours after the moon’s transit. 
* By the establishment of any port is meant the time of high water at new and full moon. 
