Fig. 5.
One advantage of the method that I propose is this, that while we are able to produce a plain intermittent light; an intermittent light of variable period, ranging from a brief flash to a steady illumination of half the revolution; and finally, a light combining the immediate occultation of the intermittent with combination and change of colour, we can yet preserve comparative lightness in the revolving parts, and consequent economy in the driving machinery. It must, however, be noticed, that none of these last methods are applicable to cases where more than one radiant is employed: for these cases, either my grandfather’s or Mr. Wilson’s contrivance must be resorted to.
1871.
[44] Read before the Royal Scottish Society of Arts on 27th March 1871, and awarded the Society’s Silver Medal.
ON THE THERMAL INFLUENCE OF FORESTS[45]
The opportunity of an experiment on a comparatively large scale, and under conditions of comparative isolation, can occur but rarely in such a science as Meteorology. Hence Mr. Milne Home’s proposal for the plantation of Malta seemed to offer an exceptional opportunity for progress. Many of the conditions are favourable to the simplicity of the result; and it seemed natural that, if a searching and systematic series of observations were to be immediately set afoot, and continued during the course of the plantation and the growth of the wood, some light would be thrown on the still doubtful question of the climatic influence of forests.