TRANSACTIONS. 251 
for the most part bright and sunny, or if cloudy or rainy, very 
mild, with south or south-west winds. 
I have also to submit a table shewing the mean monthly 
temperatures of the air and water of the estuary of the Nith at 
Kingholm Quay, and taken with great regularity by Mr James 
Lewis, for a period of about nine months, from 25th June, 1889, to 
21st March, 1890. The hours of observation necessarily varied, 
because the proper temperature of the estuary could be obtained 
only when the tide was up. For the most part they were taken 
between the hours of 9 A.M. and 4 P.M., though sometimes a. little 
earlier and sometimes a little later. 
Air. Water. Difference. 
Means. 
From 25th June to 31st July i ra Olas 61°5 +0:2° 
» Ist to 3lst August tt. at nen BOS 56-9 —2°1 
»» Ast to 30th September ... ue. a 5G 54°4 -1°8 
»> Ist to 3lst October : ae a AD 45'8 +0°3 
»> Ast to 30th November ... re . 45°8 41°6 -42 
», Ist to 14th December ... a: akon) 36°8 -1°5 
» Istto3lst January  .. ae neo IE) 39°5 iG 
» Ist to 28th February ... — sir AD 37°4 —2°6 
», Ist to 21st March a ws eau, ADFT 40°4 —2°3 
Sums oe aed a ... 429°9 4143 Mean 
— —— Difference. 
Means... ets ny ae ATST 46 LE 
From this table it will be seen that for the period from 25th June 
to 31st July the mean temperature of the estuary was a fraction of 
a degree higher than that of the air, and the same thing occurred 
again in October. In all the other months it was lower, but 
not to the same extent as in the case of the river temperature. 
Taking the whole period during which observations have been 
made, the mean temperature of the air was 47°7° and of the water 
46°, giving a mean difference of only 1°7°, instead of 4:3° as in the 
case of the river. This result might have been somewhat modified 
if the observations had been extended over the whole year instead 
of nine months, but not, I think, to any great extent, there being 
an obvious reason why the temperature of the estuary should be 
higher than that of the river as compared with that of the air, viz., 
the fact that when the tide rises it passes over the extensive tracts 
of sand which in the Solway Firth are left bare by the receding 
tide, and in sunny days become heated by the sun, to which it 
may be added that the influence of the Gulf Stream must tell in 
