TIDAL OBSERVATIONS. 507 
Synodie fortnightly tide. 
Maximum Moon’s phase, Maximum Moon’s phase, 
height New and Full height New and Full 
(calculation). (N. & F.). (calculation). (N. & F.,. 
1864. d h.- 1864. d h 1864. d h 1864. d h 
Jan. 17 4 Jan. 8 20 N. July 27 3 July 18 19 F. 
gE 22 23 10 EF. Aug. 10 21 Augr oS agi. 
Feb. 15 17 Keb. 7 GN. 25 16 ig Zui 
Mer. I 11 22) 5H. Sept. 9g 10 Ti Toon: 
16 6 Mar. 7 16 N. 24 4 Sept.15 9 F. 
a2. 6 22,32 K, Oct. 8 23 30 11 N, 
April 14. 18 April 6 2N. Bg iy Oct. 14.18 F. 
29 13 a0 1g F. Nov. 7 11 30 — aN: 
May.14 7 May 5 12 N. 22 6 Nov. 13 6 F. 
4 29 1 ar (aie Dec. 7 © 28 19 N. 
- June 12 20 June 4 oN. 21 19 Dee. 12 19 F. 
. 27 14 19 11 F. 1865. 
duly 12 9 July 3 12 N. Jam. "543 28g IN. 
30. For the sake of comparison between the calculated heights and the 
heights given by the diagram sheets, one day has been selected at random, 
and the heights computed from the results obtained, neglecting all tides 
whose maximum effect did not exceed 1 inch (-083 of a foot). The following 
are the results :— 
Heights Heights 
Calculated from Calculated from 
heights. diagram. Difference. heights, diagram. Difference. 
Cc [e) - Cc oO -0O 
1864. h ft. ft. ft. 1864. h ft. ft. ft. 
Aug. 18 o 19°06 19°05 -+oror | Aug. 18 12 13°95 18°7 +025 
I 17°96 17°65 +031 nie) 18°69 18°55 +or14 
2 15°04 14°6 +044. 14, 16°58 16°65 —0'07 
3 1r'lo 10'9 +020 15 13°00 13° —oa'lo 
4 6°93 73 0°37 16 8°86 9°55  —o'bg 
5 3°63 4°45 —o'82 17 5°18 6°05 —o'87 
6 1°65 2°4 —0'75 18 2°84 3°6 —0'76 
7 1°25 I°5 —0'25 19 I*90 2°45 —0'55 
8 3°09 2°45 +0°64 20 2°96 2°9 0-06 
9 7:28 6°15 +113 21 6°40 5°65 +075 
10 12°58 12'I +048 22 11°41 10°45 --o'96 
II 16°92 17°6 —0'68 23 16°38 16°95 —0'57 
It will be noticed that the largest differences are about the times of half- 
tide, and which can be accounted for by the diagram sheets not answering to 
the times as shown by the clock, a discrepancy of only five minutes (a very 
_ probable amount for the Ramsgate diagrams) causing at these times a differ- 
ence in heights of 6 inches. The barometer has probably been higher than 
the average on the day selected. 
31. A series of tide-records, taken near the entrance of the George’s 
Docks, Liverpool, has been supplied, on application, by the kindness of the 
Board of the Mersey Dock Estate. The heights through about twelve hours 
each, during three interruptions in the tide curve (caused by the accidental 
stopping of the clock), have been inferred from the tide-diagrams of the self- 
registering tide-gauge at Helbre Island at the mouth of the Dee. This series 
promises to give as good determinations as can probably be obtained from the 
diagrams of a self-registering tide-gauge, the sheets having apparently been 
ost carefully stretched round the drum, and the apparatus watched from 
| Ume to time. 
82. The diagram sheets are divided into quarter hours and quarter feet, 
d the heights have been read off for each quarter hour, although in the 
reductions at present in hand the height at each integral mean solar hour has 
2m 2 
