136 JOURNAL OF THE EOYAL HORTICULTURAL SOCIETY. 
continue effectual in its operation and -with no injurious results through- 
out the whole summer. In 1884 I carried out at Croydon some experi- 
ments in regard to mulching, with the following results. The experi- 
ments were made by means of two percolation gauges, each a yard 
square and containing 2^ feet of garden soil. The surface of the soil 
in one gauge was unmulched, while that of the other received a mulch- 
ing of half-rotten manure three inches thick. In every month of that 
year, with the exception of January, the evaporation from the mulched 
soil, as compared with the unmulched, was slight, while the temperature 
of the ground beneath the mulching remained considerably cooler than 
in the unmulched soil during the summer months, and particularly was 
this the case in the hottest part of the day. At night the ground under 
the mulching was as a rule slightly warmer than in the unmulched soil. 
Even at the depth of a foot the contrast in temperature was at times 
very striking — as clearly shown in the following table and in Fig. 54. 
Table showing the effect of a Mulching of half-decayed manure, 
3 inches thick, on Percolation, Evaporation, and Temperature : — * 
1884 
Temperature, &c., of soil with mulching, 
above or below that unmulched 
Earth temperature at 1 ft. 
Percola- Evapo- 
Air temperature 
Rainfall 
tion 
ration 
per week 
per week 
9 A.M. 
3 P.M. 
9 P.M. 
Mean 
max. 
Mean 
min. 
Amt. 
per week 
No. of 
days 
Gals. 
Gali=. 
Bes. 
Deg. 
De?. 
Deg. 
Deg. 
Gals. 
January 
-•12 
+ •12 
+ 0-5 
0 
+ 0^1 
48^1 
39^4 
2-80 
16 
February 
+ •44 
-•44 
+ 0-7 
0 
^0-1 
47^9 
37^4 
2^01 
13 
March . 
+ •33 
-•33 
+ 0-5 
-0^5 
-0-6 
511 
37^7 
1^54 
9 
April 
+ •12 
-12 
+ 0-6 
+ 0^4 
-0^7 
524 
371 
1-40 
13 
May . . 
+ •07 
-•07 
-0-0 
-l^O 
-2^0 
63^1 
44^0 
0-61 
10 
June 
+ •06 
-•06 
-0-2 
-1-2 
-1-9 
66^1 
48^8 
2^05 
9 
July . 
+ •18 
-•18 
+ 0^2 
-1^2 
-1-9 
71-8 
53-9 
1-68 
16 
August 
+ •18 
-•18 
+ 0^3 
-3-7 
-22 
75^5 
52-9 
112 
8 
September 
+ •02 
-•02 
+ 0-6 
-0-6 
-0^6 
670 
51^6 
2^62 
15 
October 
+ •17 
-•17 
+ 1-1 
+ 0-5 
+ 0-3 
56-0 
41-9 
1^26 
12 
November 
+ •10 
-•10 
+ 1^2 
+ 0^7 
+ 0-6 
47^3 
36-2 
173 
12 
December 
+ •04 
-•04 
+ 0^7 
+ 0^4 
+ 0-1 
45-5 
370 
2^38 
16 
Sums 
+ 1^59 
-1-59 
21-20 
149 
- 
Means . 
+ 0^5 
-0-6 
-0^7 
57-6 
43^2 
In these experiments the surface of the unmulched soil was kept con- 
stantly hoed, or the differences given in the table would, no doubt, have 
been greater than there shown. For, after all, a loose layer of surface 
soil forms in itself one of the most efficient of mulchings. It is inadvisable 
to put on any mulching, at all events, earlier than the latter half of May, 
as previous to this the w^armth of the ground is a more important factor 
in a garden than the amount of moisture in it. There are only two 
objections to mulching. It is expensive where suitable material is not 
ready to hand, and it gives the garden an untidy appearance, particularly 
where wild birds are numerous. 
Watering. — This should only be resorted to on a large scale, where it 
Quarterly Journal of the Boijal Meteorological Society, Vol. 24, page 71. 
