- TRANSACTIONS OF THE: SECTIONS. 23 
Tables of Meteorological Phenomena observed at Swansea. 
By Joun Jenkins, F.RA.S. 
_ In presenting to the British Association the accompanying records of the Meteo- 
rological Phenomena observed at Swansea, I can only hope they are of value as 
adding to the number of continuous and regular observations by a series taken at a 
position far separated from any other spot where similar observations are registered ; 
this being the only series, as far as I am aware, obtained in Wales. 
Any attempt to examine the occurrence of instrumental registries which gave ano- 
malous indications, would be occupying time with an inquiry that can be better pro- 
secuted in the study, and then when assisted by a long series of corresponding ob- 
servations. There are, however, some local conditions which it will be desirable to 
notice, that the great difference between these tables and others taken at stations 
dissimilarly situated may be explained. The first relates to temperature. 
A comparison of the temperature of the inland towns of England with the tem- 
__ perature of Swansea would surprise the casual inquirer; for instance, the tempera- 
ture of May 1844 was unusually low. On Friday the 17th, the thermometer at the 
Dock-master’s office, St. Katherine’s, London, stood at 51°, while at Swansea, in the 
open air, the mean temperature on that day was 60°. Again, on the 24th of June, at 
~ 
7 a.m., the thermometer at I.ondon stood in the shade at 70° Fahr. ; at Swansea, on 
the same morning at 9 a.m., 66°; deducting the increase of temperature for two hours, 
2°-5 per hour, the temperature at Swansea was 61°, being 9° less than at London. 
These considerable variations are to be accounted for by the position of Swansea, 
being on the margin of an extensive bay communicating with the Bristol Channel. 
The temperature of its water, being in the first example above the temperature of the 
air, imparted so much heat to the atmosphere as to modify the cold to the amount 
mentioned; while, in the second instance, the water in the bay being below the 
temperature of the air lowered the thermometric indication. 
2ndly. The direction of the wind is given for the total number of days in each 
month, from daily observations taken at 9 a.m. and 3 P.m., when the other re- 
- gistries of the instruments are made. This direction must not be regarded as the 
direction of the great aérial wave, but of the current modified by the headlands, 
which extend to the peninsula of Gower on the west and Kilvay Hill with its con- 
tiguous high lands on the east ; a correction consequently becomes necessary when 
comparing the direction of the wind at Swansea with other places not similarly cir- 
cumstanced. Careful registers kept at the Nash and Mumbles light-houses and 
Wormshead, would enable tables of equation to be constructed for such correction. 
-83rdly. The time and height of high water. 
Swansea Bay being situated at the mouth of the Bristol Channel, and having its 
shores lashed by the waves of the Atlantic, often exhibits in its undulations the im- 
pression of distant gales propagated over the surface of that broad mass of water 
long before the atmospheric disturbance itself has reached the coast. 
The height of the tidal wave in Swansea Bay is consequently dependent on the 
direction and force of the wind passing over the Atlantic, being increased when 
westerly and reduced when easterly. Another influence which belongs to this sub- 
ject, although of minor import, is the pressure of the atmosphere at the time of high 
water. La Place seems to think that this flux and reflux at Paris is attributable to 
the tidal waves which form a variable base to’the atmosphere. 
_ The Swansea tide tables contain the heights of water in the river for every day during 
the year ; but these tables being computed without reference to the disturbing causes 
alluded to, their accuracy is destroyed as often as the wind blows strongly from either of 
the points mentioned. Thus the depth of water on the bar is not always the greatest on 
_the day mentioned in the Tide Table. This discrepancy occurred during the high tide 
of 1846, when the highest tide did not occur on the day stated in the Tide Table, but, 
‘on the contrary, the second tide on the following day was the highest. Again, on one 
occasion, in the Tide Table the depth of water on Swansea bar is stated to be 23 feet, 
whereas it amounted to 30 feet; an increase in the tidal wave equal to two-thirds 
“the average depth of water on the bar at high water during the lowest neap tides. 
It is much to be desired that the amount of disturbance occasioned by the various 
winds should be ascertained and arranged as the equation table is for the sun-dial, 
so that persons who may be interested in the inquiry may be enabled to ascertain 
“the accurate height of tide at high water. 
