Jnae 7,188’. J 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
465 
in Lindley and Paxton’s ‘ Flower Garden, drawn up from Assam 
specimens that flowered in England it is accompanied by a wood- 
cut of the flower. Though haring a wide range in distribution it 
must be a rare species ; Strachey and Winterbottom found it in 
the North-West Himalaya in the province Kumaon, west of Nepal, 
which is perhaps the westernmost limit reached by the vast genus 
to which it belongs, but it has not been recorded from Sikkim or 
Bhouan, and very few collectors have met with it in Silhet or 
Assam. It must not be confounded with the D. clavatum of 
Roxburgh (D. sulcatum, Lindl., Hot. Mag. 69()2), a much more 
common species, and to which, from its club-shaped stem, the 
specific name of clavatum far better applies. The specimen here 
figured flowered in the Royal Gardens in September of last year ; 
the plant was sent from the Khasia hills by Mr. Gustav Mann in 
1885, and flowers in September.” The flowers are boi’ne in 
racemes, and hive broad rounded petals and sepals deep orange 
yellow, the lip having a bright crimson centre and a golden yellow 
margin. 
ORCHIDS AT HOLLOWAY. 
Mr. B. S. Williams’s nursery at Upper Holloway is full of 
interest at the present time, and contains an excellent display of 
flowering Orchids. During several years the large Palm house 
near the office has been specially appropriated to the Orchid exhibi¬ 
tion, but shifting the plants from their various quarters to this 
house was not found beneficial, and they are therefore more 
suitably grouped in their respective houses. The extent of Mr. 
Williams’s collection is well known to Orchid growers, and it is not 
surprising that the home stock suffices to form a display of varied 
interest over such a long period in the year, though during May and 
June the greatest number is in flower. In another important re¬ 
spect the Holloway Orchids are interesting-f.e., they are well 
grown, sturdy finely developed foliage and pseudo-bulbs or stems 
result in proportionately fine durable flowers. To this must be 
added the fact that the formation of the collection has been the 
life-work and study, the selection of species and varieties having 
been conducted with the keenest critical knowledge of their merits. 
Consequently in all the leading genera the best types only are re¬ 
presented, and it is for these that amateurs now look to nursery¬ 
men specialists when tiring of the numerous indifferent varieties 
that are unavoidably introduced with imported plants. 
Lse’ia purpurata has been made a special feature, both plants 
and varieties being extremely good ; and a pretty group is formed 
at the entrance of one of the houses with these ; Cattleya Mossiae 
varieties, Masdevallia Veitchi grandiflora, bearing twenty flowers ; 
M. Harryana, M. Lindeni, Dendrobium thyrsiflorum and chryso- 
toxum, Odontoglossum vexillarium, capitally grown ; the gi aceful 
Oncidium sarcodes at the back, the greenish white Cyrtochilum 
stellatum, Maxillaria grandiflora, Aerides Warneri, Coelogyne 
Massangeana, and Scuticaria Hadweni. In another house we find a 
group comprising several similar plants, with Cymbidium Lowi- 
anum bearing five long racemes ; Cypripediumbarbatum superbum, 
having eleven fine rich flowers ; and C. b. nigrum, with nine dark 
flowers ; Laelia cinnabarina, Dendrobium suavissimum the sweetly 
scented Burlingtonia fragrans, Anguloa Clowesi and A. Ruckeri, 
Dendrobium Dalhousieanum, with seven racemes of large flowers ; 
Brassia verrucosa, with eleven racemes ; Brassia Keiliana tiistis, a 
dark form ; Brassavola lineata, and the wonderful Lailia elegans 
prasiata, which is one of many grand forms of L. elegans that 
enrich the Holloway collection. In a third house Vandas pre¬ 
dominate, suavis Hrubyana, tricolor Patersoni, insignis, and the 
Glen variety being fine. Calanthes veratrifolia Dominiana, 
Textori, and Masuca grandiflora are represented by good plants, 
together with numbers of choice Cypiipediums, Phalmnopses, 
Thunias, Saccolabiums, Dendrobiums, e'ec. In the cool house 
Odontoglossums of the best varieties afford some bunches of 
spikes, beautifully contrasted with the richly tinted Masdevallias, 
while in one house is a valuable group of all the principal hybrid 
Cypripediums and rare species in the best of health and flowering 
well, C. selligerum majus being uncommonly good. Ferns, stove 
and greenhouse flow'ering and foliage plants, are in excellent 
condition, and the nursery altogether is well worth a visit.—Z. 
THE EFFECT OF VEGETATION ON RAINFALL. 
An interesting pamjffilet, entitled “The Natural Law of Relation 
Between Rainfall and Vegetable I.ifc, and its Ai)plication to Australia,” 
has just been {)roduced by Fran/, A. Velschow, C.E., of Copenhagen 
(Stanford, Charing Cross), in which, in the course of some forty pages, the 
peculiarities of the Australian climate are fully discussed. By comparing 
the recorded rainfall in different districts the author show's that as the 
moist air flowing in to land fmm the ocean rises at a short distance 
inland above what he terms a “ dry air cushion,” through which rain 
can only penetrate by the greatest difficulty—namely, after the air has 
become partially saturated, lie contends that a gi'adual extension of 
the moist boundary could be effected by planting trees largely, as a 
circulation would then be established that would result in more regular 
and frefluent rains. The subject is summaiised in the following 
remarks :— 
“ Over the dry .and warm tracts of Australia the general Heath-like 
vegetation is marked by a pervading blue-green colour, with dull leaves 
so arranged upon the plants as to afford but little shade. The Euca¬ 
lyptus, or Gum Tree, and other trees and shrubs bearing bright honeyeil 
flowers, together tvith thickets of Acacia and Marsh Oaks, give a pecu¬ 
liar character to the forest lands. As the foliage of these trees generally 
consists of heavy leathery leaves covered by a thick cuticular coating, 
the evajtoration from them is exceedingly small, and it is therefore 
strange that the Gum Tree has been thought to possess the quality of 
removing the moisture from marshy places by Iteing planted there. 
This is evidently owing to the circumstance that Gum Trees, when felletl, 
are generally found filled with water in abundance ; but this is always 
the case with the vegetation found in deserts or very arid zones, more 
especially with the Cactus plant, which has been proved to give no 
ev.aporation at all, so to speak ; and they thereby becfjme prepared to 
withstand excess of dry weather. As the camel before entering on his 
journey across the desert stows away a large quantity C)f water, so these 
trees of the desert prepare themselves for the dry season by taking in 
water ; but, like the camel, they economise this supply, being protected 
against a too rapid evaporation by their cuticular coating. 
“ It is to the small degree of eviiporating power of the Australian 
vegetation generally that the irregularity of the rainfall may be consi¬ 
dered due, and the rainfall could therefore be highly improved if by 
some means or other we could substitute for the itresent vegetation 
another possessing a high degree of evaporating power. 
“ Looking upon the subject at large the question before us may be 
defined thus : Is the want of trees exhaling much moisture in Australia 
due to the impossibility of their growth there, or is it due to accident ? 
It is well in this respect to notice how the earth's surface has been 
divided into six distinct regions, each with its own particular flora and 
fauna, more or less independent of latitude and temperature, but prin¬ 
cipally caused by the insurmountable barriers formed against Gieir 
further spread by mountain ranges, deserts, and oceans ; and that it 
has been found that trees transplanted from one of these regions into 
another grow there equally well, or even better, than in their aboriginal 
home. Among these regions Australia, with the surrounding islands, 
forms one, and it seems therefore highly probable that European deci¬ 
duous trees, or any other kind of trees of high evaporating power, would 
thrive equally well in the south-e.astern temperate i)art of Australia, as 
in Europe. The desert theory now put forward serves to prove that the 
climate would be cha,nged if we could manage to establish forest belts 
of deciduous trees over this south-eastern part of Australia. Along the 
coast deciduous trees grow exceedingly well, as can be seen in the 
botanic.al and private gardens, and there can be no doubt that they will 
grow equ.ally 'well wheresoever the ground is sufficiently moist. It 
might, therefore, be a practicable undertaking to commence plantations 
at the coast, stretching thence further and further inland, the effect 
being that of breaking up the border of the air-cushion, so as to permit 
the rainfall along the co.ast to reach further inland. 
“ The difficulty would evidently at first be where to find enough of 
moist sitil to start the plantations. But the various colonies have voted 
considerable sums of money for the conservation of water in general, 
and particularly for the irrigation of the Murr.ay-Darling River. The 
evaporation from the country hereby brought into cultivation would in 
itself be very considerable, and could be liighly augmented by planta¬ 
tions along this line of irrigated country. In this manner the air- 
cushion, too, would be likely to be broken along this line, the ultimate 
effect of works of plantation on both sides of the district being tlie 
entire change of climate in south-eastern Australia. 
“ To find out the most suitable trees for planting, it would be neces¬ 
sary to carry out careful measurements of the evaporation from different 
kinds of deciduous and other trees by planting them in large covered 
Ixixcs constructed for this purpose. Among those which hereby show 
the highest amount of eva)>oration such must be chosen for plantation 
as will grow most easily in the colonies, besiiles being useful as timber 
trees. 
“ It might then even be found that the jiroject of est.ablishing tlic 
growth of these trees in Australia would be materially assisted by 
Nature, according to Darwin’s theory of the survival of the fittest, .as 
it of late years has been found that in northern Europe the Beech is 
gradually superseding the Oak, which was formerly the domin.ant tree. 
Likewise in Australia, if trees of a more vigorous growth than the 
native tiecs are introduced the ultimate extermination of the latter 
may be anticipated. 
“ From a geological point of view Australia is recognised as the 
remnant of some former extensive continent. By being situ.ated in 
the central most elevated region of this continent Australia would in 
.all probability have formed a desert exactly similar in jiosition to the 
desert of Gobi in Central Asia. When afterwards the surrounding 
country became submerged this central [lart preserved the onoc- 
attained ch.aracteristic fc.atures of a desert—namely, a non-evaporating 
vegetation covered by .an air-cushion, in spite of the oceans which ha^e 
gradually ajiproached the borders of this desert. In this w'ay it is to 
be explained how it h.as been brought about that we nowail.ays find 
ourselves opposite this phenomenon, so extraordinary to all scientifio 
minds, of a large desert island id.aced in the centre of the largest ex¬ 
panse of tropical se.as. But the greater tins absunlity appears the 
