498 REPORT—1868. 
15. The Committee recommend that this Table should be printed for 
general use in the reduction of tide observations. A second Table, which 
will be described later, has also been drawn up. Part of it, amounting to 
2 ees? : F 
about 6x5 of the whole, is given here as a specimen. By aid of these 
Taste or Comparative Mzan Sorar AnD Mean Lunar Hovrs, 
ae Hour M (y—o). 
° 
HS] o.| 1] 2] 3.] 4.] 5.| 6] 7] 8] 9-] 10.) 21.) 12.] 13.) 14.) 15.| 16.) 17./ 18.) 19.| 20.) 21.) 22. 
YYPYP YD S&H RM Oe ee ee Oe 
WS) SU O6O 60-3) Syn FSG) Set OOOO Gri aN EO 
16|14|16|13|16|14|)17| 15/16/16] 16/17/15 /17|15] 17/15] 317|14| 16/14) 15] 15 
15/15 |15|315|14)15]15|16)15 | 17) 15) 17 16/16/16|16| 16/16) 16) 14] 16| 14/16 
13|16|314.|15]15|14|)16|314)16)15]17|)15/17|15|27/15 16/17] 15|17] 14] 16| 14 
15|14]15|14| 16| 14] 15] 15|15|16|15| 16) 16) 16) 16/16) 15/17/16) 16) 16) 15 | 16 
14| 16| 13] 16|14| 16/13] 16] 14] 16] 45) 15)27) 15] 17/15/17) 15] 17) 15|17| 15 | 16 
15|15|15|14|16/314/15]14]15|315]15| 15 | 16 16}16/17|15|17|15/16|16| 16) 15 
16/14] 16| 14] 15/15 |14|16|13|16/14)16) 14] 17) 15/17) 16| 16) 16) 15/17) 15) 17 
15|16| 14) 15|14|15]15]15|25|14]16| 14] 16 | 14) 16/16 | 16 16| 16} 16) 16) 17] 15 
16|15| 16/14] 16|13]16/14| 16|14]15|)15|315] 15) 14/17/15) 317|15|17| 15) 17| 16 
16|16| 16 | 16| 14) 16}13]16| 14] 15] 14) 15]15]15|15|15|17|15]17|15| 17) 15] 16 
15|17/315|17/15|15|15| 14/15 | 14|16| 13 | 16) 14] 16| 14] 16) 16/16) 16) 15) 17/15 
17/15] 17] 15|17/14|15|15|14| 16| 14] 16)13)16|14] 16/13] 16) 16) 16) 17) 15) 17 
16| 16/16/16] 15]17|14|16]14]15]15/15]15|14]15|25]15|13|17|315|17| 16| 16 
15|16|317}15|17|15|17|14| 16/13) 16| 14/15] 15] 14] 16) 14 16/13/17) 15) 17|15 
17|15|17|16/16|16/16|16|15|15|14)15]14|16)14/15]15)15|15|14| 16] 16 16 
15|17| 15|17| 15/17) 15|16|47| 14| 26) 13} 16] 14) 16) 13/16) 14/16 | 14) 14) 17| 15 
17|15|17|15|16|16|16)15|17| 16/15 | 15] 14] 16) 14/15/14) 15) 14 16| 14] 15) 16 
17|16|15|317|15/17)15]17|15|17]15| 16) 14/15] 15/14] 16) 13 | 16) 14) 16) 13 16 
16| 16|16|16| 16| 16} 17| 15) 17] 15] 16| 16/15] 314] 15|15]15| 15] 14/16) 14| 16] 13 
16] 15|317|15|17|15|17|16| 16/16) 15/17/15) 16/13] 16) 14) 16] 14) 15) 15) 14) 16 
14/16] 15|17|15|16|16| 16) 16| 16] 16/16/17] 15] 16) 13] 16/14) 15) 14) 15) 15/15 
14|15|15|16| 16] 15|17/25/17/15|/17/15|27| 16/16/15] 14) 15) 14 16] 13) 16| 14 
16|13|15|15|16|317|15]17| 15|17|15|17|15|16| 16/16] 15/14) 16 | 14] 16 | 13 | 16 
14| 16] 13| 16] 14] 17|16/ 16] 16) 16/16/16) 16/15) 17) 15) 27] 15) 45|15/ 15/15] 14 
Tables, with a set of rules for use to be appended, it is anticipated that an 
accurate and extended reduction of tidal observations for any sea and any - 
complete year will become a very simple matter. For the present we 
confine ourselves to the statement of what has actually been done for the 
year 1864 and the harbour of Ramsgate. 
16. A datum line 10 feet below the previously supposed mean level was 
chosen*, and the height of the curves, marked by the self-registering tide- 
guage, was measured from this datum line in feet and decimals of a foot for 
each integral mean solar hour of the year, and entered in the Table. A 
period of 369° 3%, or rather more than a year, was taken as being to the 
nearest hour twelve and a half lunations or twenty-five periods of spring 
and neap tides, and therefore giving a least possible amount of influence of 
the mean lunar and solar semidiurnal tides, each on the sets of averages 
used in the calculation of the other. A period of 358% 6" was chosen, for a 
similar reason, for the lunar elliptic semidiurnal tides, 
17. These averages were taken according to the following rule. First 
for the S tides, twenty-four means of the heights at 0", 1", 2",.... 23” of 
S hours (or ordinary mean solar time) were taken. Next for the M tides 
twenty-four averages were taken of heights grouped similarly according 
Bue true mean level for the year 1864 has been found to be 10°192 above this datum 
line, or 192 of a foot higher than was supposed. 
