i a eel 
ON EFFECT OF WIND AND ATMOSPHERIC PRESSURE ON THE TIDES, 511 
were 12 inches or more above the predicted heights as given in Holden’s 
Tables, when the wind did not exceed a force of 3 on the Beaufort scale 
(as reduced from the mean velocity), and the barometer was 0°25 inch above 
or below the average. 
Low water of spring tides is taken as 9 feet below the Old Dock sill. 
Holden’s Tide Tables appear to give the predicted tides too low, 78 per 
cent. of the tides being above those given in the Tide Tables, a mean of 
1-04 foot, and only 22 per cent. below—a mean of 0°46 foot. This, to 
a certain extent, affects the results obtained in the above table. 
BAROMETER AND TIDES. 
Summary. 
| = : Mean varia-|Mean varia- 
| N ped of aoe tion of tion of 
| — K Tide from | Barometer 
affected in above arated fi 
one year | L.W.S.T. Le piehie er 
height average 
Ft. In. In. 
High Bar.—Low Tides | Boston . 65 19-02 9°81 “403 
Low Bar.—High Tides { Hull. 40 19°55 8°26 “358 
- - Sheerness . 35 15°58 15°20 “420 
- - Portsmouth 64 12:28 12:22.-") © “383 
fe = Liverpool . 36 24°46 16°78 “445 
240 18°17 1245 | -402 
The average result is equal to a variation of 13 
half an inch variation in the barometer. 
inches of the tide for 
Number of | Mean rise Secret cam ge Ea 
sk, Tices of Vide | Tide from Baroilleter 
affected in above védicted f 
one year | L,W.S.T. 7 : om 
eight average 
Ft. Th. In. 
High Bar.—Low Tides] Boston . 45 19°37 10°13 387 
Low Bar.—High Tides f Hull. “ 48 18°83 7:76 379 
7% PS Sheerness . 72 14:12 14:27 451 
an a Portsmouth 11 10°30 11-29 “314 
a _ Liverpool . 9 24°99 12°33 “390 
185 17°52 11:15 B85 
Average result equal to a variation of 15 inches of the tide for half an 
inch of the barometer. 
The above results show that out of an average of 425 tides recorded ina 
_ year at five ports varying from the calculated height 6 inches and upwards, 
coincident with a variation of 0-25 inch of atmospheric pressure in calm 
weather, 240, or 56 per cent., were lowered when the pressure was above, 
cor were raised when it was below the mean ; and 185, or about 44 per 
cent., were influenced in the opposite direction. 
