152 Messrs Coldstream and Foggo’s Meteorological 
3. Humidity. Fahr. Tlier. 
Mean difference between the two Thermometers, 4°. 700 
Maximum ditto, 13.000 
Minimum ditto, 0.000 
4. Fain, 1.32 inchesin 14 days. 
5. Winds,... NE. 3, E. 4, SE. 1, SW. 4, W. 8, NW. 1, Yar. 9 days. 
Remarks. 
3d . — This day was particularly fine : the brightest sunshine prevailed. 
The following thermometrical observations were made about 2 p. m. 
Temperature of air in the shade, - - 66°.0 
of dew-point, - - 47-0 
of garden mould exposed all day to 
the sun’s rays at the surface, 121.0 
of the same, at the depth of 2| inches, 81.5 
1 foot, 76.0 
18 inches, 67.0 
2 feet, 63.0 
of garden mould always in the shade, 
at the surface, - - 62.0 
of the same, at the depth of 2 inches, 61.0 
1 foot, 60.0 
18 inches, 59.5 
2 feet, 58.0 
In page 67. line 9. of this Number, in the paper on Solar Fadiation, 
the temperature of the air in Mr Campbell’s observation should be stated 28°. 
4 th . — This evening, at sunset, there was a gorgeous display of colour in 
the west. Amongst the numerous tints that appeared, the green was particu- 
larly distinct, and remained so for a considerable time. The sky was filled 
with rather dense cirro-strati. 
10 th . — Since the 4th, the weather has been unpleasant ; the pressure gra- 
dually decreasing, and the temperature of the dew-point rising. To-day, at 
noon, the latter was 53°; on the 4th it was 41° *. Barometer at 4 p.m. 29.30. 
* During the summer months, our observations on the dew-point were 
made by means of a contrivance similar in all respects to that which Mr Tho- 
mas J ones has proposed in a paper read lately before the Foyal Society of 
^London, as a new Hygrometer. We used a common thermometer, with a 
bulb blown of black glass, the upper half of which was covered with muslin, 
and surrounded with a rim of silver, fitting closely the largest circumference, 
and so hollowed out, as to be capable of holding a small quantity of a liquid. 
Sulphuric ether being dropped upon this surface, the whole bulb was quickly 
cooled, and the deposition was visible on the lower and exposed surface. This 
instrument is most easily used. Even in the driest weather in July, when 
we had the dew-point sometimes 27° and 30° below the temperature of the 
air, we could obtain a deposition with eight or ten drops of ether in the course 
of two minutes. In general, we employed only five or six drops of ether, 
and completed each observation in little more than one minute. We had used 
this instrument for four months before we heard of Mr Jones’s invention; but 
that gentleman’s paper was read to the Foyal Society before we had com- 
pleted our design. 
