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POPULAR SCIENCE REVIEW. 
which was attributable to the remarkable fall of snow on the 11th, which 
(as is not infrequently the case when snow falls heavily with an air tem- 
perature of 32°) was very dense, and almost sticky, from its semi-fluid, semi- 
frozen state : such snow, of course, adheres with especial closeness to trees 
wet with the rain which preceded the snow ; then came frost, binding all 
firmly on, until even the telegraph wires were as thick as one’s arm, and it is 
no wonder the break-down was almost universal in the district where the 
above conditions were fulfilled, which was generally the case in North Sussex, 
Kent, Surrey, Middlesex, Herts, and Oxford. 
The Minimum Thermometer on Grass. — Mr. Symons, the author of “ British 
Rainfall,” states that the instructions hitherto issued on the placing of the 
minimum thermometer on grass, have been rather vague and require more 
strict definition. He thinks that probably Mr. Glaisher’s paper on the 
“Radiation of Heat at Night from the Earth,” [Phil. Trans. 1847,] affords the 
best basis for instruction upon the subject. As meteorology is now becoming 
as popular a pursuit as any we know of, we subjoin Mr. Symons’s remarks for 
the benefit of our readers. “We may remark,” he says, “that when com- 
mencing observations with a thermometer on grass, we made use of a patch 
of turf about 2 ft. in diamater, and on subsequently removing the instrument 
to a large grass plot, the recorded minima were so much lower that we rejected 
all the previous readings. Has any one tried the effect of simultaneous 
readings on large and small surfaces of grass ? As to the effect of variations 
from the length and quality of grass, the results arrived at by Mr. Glaisher 
were that long grass gave 1°T lower min. than short, and that if the ther- 
mometer was even one inch above the grass it would be 2° ‘8 •warmer. There 
are several points well worthy of consideration. For instance, would it be 
well to adopt some substance of high, but constant, radiating power, and not 
like grass varying with its daily growth ; or is it better to let grass, which 
has been our radiation measure for some years, remain so, but try to make the 
conditions uniform at all stations ? Again, the spirit minimum often reads 5° 
higher than Caselli’s mercurial minimum. Is it not imperative that all 
should use one or the other ; or, at any rate, that it should always be stated 
which is used ? Lastly, the Scottish Meteorological Society recommend a 
spirit minimum whose bulb is black glass, while those used in England are 
mostly, if not all, transparent spirit, in clear white glass. Comparison of 
these instruments should be made, and the results will find ready insertion 
in these columns.” 
Weather Foreknowledge is the title of a clever little pamphlet published 
by Houlston & Wright, and which gives much valuable information upon 
the subject of Weather-wisdom. We do not think all the writer’s theories 
are correct, but no one who has read his essay can fail to become to some 
extent a good weather-prophet. We commend “ Weather Foreknowledge” 
to our readers’ notice. 
