68 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
[ January 28, 1892. 
the observations themselves it may not be out of place if I preface this 
modest inquiry with a brief history and description of the percolation 
gauges with which they were made. 
“ About ten years ago, when residing at Croydon, I was desirous of 
testing for horticultural purposes the effect of mulching upon the 
moisture and temperature of the ground. I consulted my friend Mr. 
Baldwin Latham, M.InsG.C.E., also a resident in Croydon, and well 
known as a leading authority on all matters relating to underground 
water, and he advised me to employ for this purpose percolation gauges 
similar to those he had then in use in his own garden. Acting upon Mr. 
Latham’s suggestion 1 had made two open slate cisterns, each 3 feet 
square and 3 feet deep. These were sunk into the ground to within a 
few inches of their upper edges, and in the centre of the bottom of each 
cistern was inserted a pipe which led into a small covered chamber at 
the side. Over the bottoms of these cisterns I placed a layer of pebbles, 
and over these some gravel, the two layers taken together being 3 inches 
deep. The cisterns were then filled up with ordinary garden soil to the 
depth of 30 inches, or to within 3 inches of the top of them. The stones 
and gravel were introiueed beneath the soil with a view to equalise the 
drainage over the whole area of each of these percolation gauges, for 
such they had now become. In the chamber at the side under the ends 
of the conducting-pipes were placed cans capable of holding several 
gallons of water apiece, to receive the drainage from the gauges. In the 
centre of each gauge was inserted one of Symons’ earth thermometers, 
with its bulb at the depth of 1 foot below the surface of the soil. 
“ I was so much pleased with the working of these gauges that when I 
removed to Berkhamsted, about six years ago, I brought them with me 
and had them sunk side by side in my present garden in a line with my 
rain-gauges and other meteorological instruments. The mulching ex¬ 
periments having been completed, I thought that it would be interesting 
to employ them here as permanent percolation gauges. One of the 
gauges was accordingly filled with some of the lightest soil, and the 
other with some of the heaviest soil obtainable in the neighbourhood. 
In all other respects, however, the arrangements are precisely the same 
as those I have described as having been used for the experiments at 
Croydon. The light soil is composed chiefly of disintegrated clay, 
vegetable earth, and numerous flints ; while the heavy soil is mostly a 
stiff yellow clay with an equally liberal addition of flints. Both are 
natural soils and were placed in the gauges as nearly as practicable in 
the same order they occupied in the spots from which they had been dug. 
In order to prevent cracks forming in dry weather, the surface of the 
soil in each gauge is hoed regularly once a week to the depth of about an 
inch. This also serves to keep down weeds. 
“ Although the gauges were filled during the autumn of 1885, nearly 
two and a half years were allowed to elapse before any regular measure¬ 
ments were made, as it was considered advisable to allow the soils 
sufficient time to settle dosvn and become fairly consolidated. Of course 
in such confined spaces there is little hope of their ever becoming any¬ 
thing like as firm as in their natural state. 
“ The total rainfall for the whole period over which these observations 
extend (April, 1888, to March, 1891) was 73|- inches. Of this amount 
47 inches, or about 63'9 per cent., passed through the 2^ feet of com¬ 
paratively heavy soil, and inches, or 59 2 per cent., through the same 
depth of lighter soil; so that the drainage through the more retentive 
soil exceeded that through the lighter soil by altogether 3^ inches, or 
7J per cent. It therefore follows that the evaporation from the surface 
of the heavy soil must have fallen short of that from the surface of the 
light soil by precisely the same amount—viz. 3^ inches. 
“ During the three summers, commencing with April and ending with 
September, the totals of the heavy soil drainage amounted to 45 per 
cent, of the rainfall, whereas that tarough the light soil was only 36-9 per 
cent., or 8'1 per cent. less. The total evaporation from the light soil 
during the same period exeeeded the drainage through it by about 
10 inches, whereas from the heavier soil it was only 4 inches in excess of 
the drainage.” 
Similar data are given in tabulated form for the winter halves of 
three drainage years beginning in each case with October and ending 
with the following March. “This is the period when there is least 
evaporation, and therefore when the drainage is at its maximum Indeed, 
it might almost be said that our underground water supply would never be 
replenished at all were it not for these winter rains ; for in Nature it is 
seldom that the rain whieh falls during the rest of the year has any 
chance of finding its way permanently into the ground. The difference 
between the quantities passing through the two soils during this period, 
owing to the small amounts evaporated from their surfaces, will be seen 
to have been but slight. In fact the drainage through the heavier soil 
was 85’4 per cent., and that through the lighter soil 84-G per cent, of the 
aggregate rainfall, or a difference in favour of the heavier soil of barely 
1 per cent. The differences between the quantities evaporated conse¬ 
quently also eome out small.”— {From the “ Transactions of the Hert¬ 
fordshire Natural History Society f December, 1891.') 
RHODANTHES. 
These graceful annuals are very useful for decorative pur¬ 
poses, and last a long time in good condition. Five-inch pots well 
filled with healthy plants, when crowned with their pink and 
white flowers, always command admiration. I took a great liking 
to them a few years ago on seeing them exposed for sale in Covent 
Garden Market. I was, however, not very successful in my early 
attempts to produce plants equally good, but after a considerable 
amount of attention and some failures I succeeded at last. I 
found out eventually that the two greatest mistakes made in my 
first attempt were to thin the seedlings too severely, and to give 
too much water in the early stages of growth. 
The present is a capital time to make a sowing to produce 
flowering plants in the early summer months. I find 5-inch 
pots are the size in which the plants are most useful, and 
as these Rhodanthes require but little root room, and make 
very slender top growth, the seed should be sown thickly 
enough to produce plants half an inch apart over the 
whole surface of the soil. When the seedlings are about an 
inch high there seems a great temptation to thin them to a 
greater distance apart ; but if this be done the mistake will soon 
be discovered, as the flower stems get thin and tapering as they 
extend in length. A compost consisting of two parts loam, one of 
old hotbed manure, and one of leaf soil with a little sharp sand 
added suits them admirably. The seeds should be just covered 
with fine soil, which, when slightly pressed down, ought to be about 
half an inch from the rim of the pot. Af ter watering the soil through 
a fine rose, the pots should be placed in a gentle heat, and as soon 
as the seed has germinated ought to be placed on a shelf near the 
glass to ensure a sturdy growth from the beginning, as ultimate 
success depends in a great measure upon this practice. 
The seedlings should be watered through a rose when they 
require it till they are 2 inches in height; after that stage is 
reached the use of the rose may be discontinued, but the soil must 
be kept rather dry till the plants are about G inches in height. By 
that time it will be found root action has become pretty active, 
and larger supplies of water needed. Weak liquid manure should 
also be given from this stage onward till the flower buds are 
beginning to open, when it should be discontinued. Occasional 
applications of clarified soot water are also very beneficial in giving 
the foliage that deep green hue which is so attractive in plants of 
this description. A shelf in an ordinary greenhouse or cool vinery, 
where they are not on a level with the ventilators, is a suitable 
one for the plants at this season of the year ; but later sowings 
will succeed admirably in cold pits. 
The only support the plants require is to place four small sticks 
round the edge of each pot with a twisted piece of raffia grass 
carried from one to the other, from 4 to 6 inches above the rim 
of the pot. This effectually supports the slender stems, and yet 
allows the plants to grow in a natural manner. When in flower 
these beautiful annuals are suitable alike for placing singly in 
vases, arranging among other plants to form groups, or for using 
in a cut state. R. maculata and maculata alba are the varieties 
I have previously grown ; but I see by the catalogues there are 
double red and double white forms. These I intend to try this 
season.—H, D. W. 
EXPERIMENTS IN TREATING THE POTATO 
DISEASE. 
{Continued from page 41.) 
Havinh already discussed the cause of the Potato disease, it 
now remains to combat the enemy. This can only be effected by 
precautionary measures, for such only are the so-caUed remedies, 
inasmuch as once the fungus has gained access to the internal 
tissues nothing can possibly do more than prevent the spread of 
the disease, no remedy wholly destroying the parasite without 
killing the host. 
Dr. Lang suggested, in 1858, the moulding-up of the Potato 
plants as a protection against the conidia being washed down to 
the tubers. This was not followed to any great extent until it was 
strongly advocated by Mr. Jensen of Copenhagen, and supported 
by Professor Plowright. Mr. Jensen’s system has the advantage 
of being possible only where the soil has been thoroughly worked 
and made friable. Then the rows should be 30 inches apart, the 
plants thus having sun and air assured to them, inducing a sturdy 
plant, solidified growths, and disease resistant. The first earthing 
is done in the ordinary way, except that it is to be flat on the top 
instead of, as in the ordinary way, furrowed hollow up the centre. 
The rounding is to give rain a chance to wash the oospheres or 
conidia into the furrow spaces between the rows, where they are 
powerless for mischief, except by contact with the roots, which at 
the first moulding and for some time afterwards are practically 
nil, and where they can only germinate to perish. It is not the 
oosphere or conidia liberated (zoospores) that can live without 
germination in the presence of warmth, atmospheric air, and 
moisture, but the warted “ fruit,” and that cannot hold the 
oospheres, prevent their escaping unless buried, and then it may live 
four years without losing its germinating power. The protective 
moulding is to be done as soon as diseased spots appear on the 
