108 Gibbs: Rainfall Records at Wirksworth, Derbyshire. 
It will be noticed that at Wirksworth, the Winter is the 
wettest quarter; at Burton, the Summer, and at Wetwang, 
the Autumn; while at all three stations the Spring is the 
dryest. At Wirksworth and Burton, the figures for the Winter 
and Summer quarters are practically reversed. This may 
probably be accounted for by the greater proportion which 
thunder-rain bears to ordinary cyclonic rain in the lowlands 
as compared with the hill country ; thunderstorms being of 
course more frequent in the summer months. 
The last point which I wish to bring out is to answer the 
question ‘‘ What is the true average yearly rainfall at Wirks- 
worth.” ? The average for the 16 years, 1895-1910 was 
33°68 inches, that for the 21 years ending Ig10, 32-73 inches, 
but even the longer period is not sufficient to form the basis 
ofareliable average. Thisis proved by comparing the averages 
at Burton and Wetwang for the years 1890 to 1910 with the 
complete series of 35 and 29 years which the records respect- 
ively cover, the figures being :— 
Burton 1890-1910, 24-70 in. 1876-1910, 26-22 in. 
Wetwang 18go-I9gI0, 25-40 in. 1876-1910, 26-28 in. 
The considerable deficiency in the average for the shorter 
periods is accounted for by the fact that the omitted years, 
viz.: at Burton, 1876-1889, and at Wetwang, 1882-1889, were 
with very few exceptions, years of more than average rainfall. 
As Burton is not very far distant from Wirksworth (about 20 
miles) and 35 years is generally considered a fair period from 
which to deduce an average, I have used this record from 
which to deduce the probable true average rainfall for Wirks- 
worth. As stated, the Wirksworth average for the years 
1890-1910 is 32°73 inches; the Burton average for the same 
period is 24-70 inches. The Wirksworth average is therefore 
1-325 of the Burton average. Applying this ratio to the Burton 
35 year average of 26-22 inches we get an estimated 35 year 
average for Wirksworth of 34-74 inches. 
7O: 
Hull Museum Publication No. 90, being the 42nd Quarterly Record 
of Additions, contains pictures and illustrations of old shipping views, 
Roman remains, numerous short notes, and a reprint of Mr. Sheppard’s 
paper in The Naturalist on Early Microscopes. A. Brown & Sons, 28 pp., 
nGE 
Guide to the Collection of Gemstones in the Museum of Practical 
Geology, by W. F. McLintock. London: Fisher Unwin, 92 pp., od.— 
This Guide deals not only with the collection as displayed in the Museum, 
but also with the general properties of gemstones, the characters by which 
they may be identified, the various methods of cutting them so as to 
enhance their beauty, and the processes by which they have been imitated, 
modified, and in some cases artificially formed. All the more important 
gemstones are represented in the Collection, both in the rough state and 
also cut, polished, and, in a few cases, mounted as articles of jewellery. 
The Guide is illustrated. 
Naturalist, 
