MADE AT CAltNWATH, LANARKSHIRE. 289 



Dew-point. — The mean dew-point at Winterlaw at 9 a.m. was 

 42°-5, and at Gallowhill 42°-0, and at 9 p.m. 42°-2 and 42°'0 

 respectively, thus shewing at both hours, but particularly at 9 a.m., 

 a greater amount of vapour in the air inside than outside the wood. 

 These results, taken in connection with those of the temperature, 

 shew that in the spring and early summer months the air inside 

 the wood is warmer and moister than that outside, but during the 

 fall of the year it is colder and damper. The months during which 

 the excess of vapour in the wood was greatest were September, May, 

 June, July, and August. 



It is scarcely necessary to dwell on the importance of these results 

 in their relation to the interspaces in woods which are sheltered more 

 or less from the wiud, whether these interspaces be over treeless 

 patches, or over patches of wood where the trees are of less height 

 than those surrounding them. From their obvious connection with 

 the rainfall, the temperature and humidity of the air of these inter- 

 spaces, which differ so markedly from those of the surrounding air 

 outside the wood, call for fuller investigation, and for this reason 

 the observations made last year at Camwath should be continued 

 for at least another year. 



But other points call for inquiry in carrying out this investiga- 

 tion. (1.) The daily extremes of temperature, and the humidity of 

 the air at a station in the interior of the wood, not cleared of trees 

 as at Winterlaw, but covered with the usual complement of trees ; 

 (2.) Underground temperatures at say three depths at the stations of 

 Gallowhall, Winterlaw, and the new proposed station; (3.) The 

 evaporation at the same three stations ; and (4.) The temperature of 

 the trees themselves, ascertained by means of thermometers per- 

 manently fixed in them, in the manner adopted at the Forest 

 Stations of Bavaria. 



