416 

an obvious criticism that the basis of calculation | 
may be of changing value owing to changed condi- 
tions by stating that the percentage cost of materials 
in a cottage in 1914 and 1921 was found practically 
identical. From the diagrams the increased cost of 
a cottage due to variation in the market price of 
a material can be at once ascertained. We imagine 
that variations in human output are a good deal less 
amenable to graphic representation. Apart from this, 
however, a great deal of useful matter on relative 
costs and methods of calculation will remain truly 
recorded in this publication. 
The notes which constitute the report on cob and 
fisé building form an interesting epitome of a subject 
which came into great prominence during and after 
the war, when bricks were prohibitive in price and 
the bricklayer was laying them at a minimum rate 
never contemplated. It is very unlikely that the 
methods of building described will ever become 
general, though in special local circumstances they 
will continue to have value. 
The contributors to these notes write quite dis- 
passionately, a fact which adds greatly to the value 
of the concise information given. Various methods 
used are explained in detail with dimensioned sketches 
of the simple shuttering and tools used in this con- 
struction, while photographs of cob and pisé cottages 
show how satisfactory a home it is possible to pro- 
duce, even for two-storied buildings, direct from 
natural earths. Walls, which may be of lumps 
from a mould or formed in situ, are one or two feet 
in thickness and the houses are said to enjoy a very 
equable temperature and to remain dry, but a brick 
or concrete foundation about a foot high is necessary. 
NATURE 

The recent times of stress have produced a great 
many new types of building, but if we are to judge 
[MarcH 24, 1923 
from American experience it would seem that, taking 
capital and current cost over a decade, the ordinary 
brick still holds its own against later competitors. 
Houses or cottages having been constructed, it 
is necessary to provide heating appliances, and range- 
makers and others will find much useful information 
in the third of these reports.» The necessity for the 
conservation of fuel energy during the war pro- 
vided the stimulus for this useful investigation. It 
is common knowledge that the kitchen range is, in 
most houses, the main and most wasteful coal con- 
sumer, and it is surprising that range-makers have 
not before now turned their attention to the pro- 
duction of more efficient designs. This may be due 
partly, as the author points out, to the incompati- 
bility of running economy and initial low cost of 
apparatus, but if capital and current costs were 
simply tabulated the purchaser would soon realise 
the ultimate cheapness of a range designed to utilise 
more heat units. 
The purposes of a range for boiling, baking, water 
heating, and perhaps warming, render, the report 
tells us, a really economical design impossible, and 
attention should therefore be directed to the con- 
sideration of any means for separating these functions 
which might be practicable at least in large establish- 
ments. These functions were tested independently 
both from a broad physical and also from a purely 
culinary standpoint. Considered as separate func- 
tions, only 2} per cent. of the heat is transmitted 
to the oven, 12 per cent. to heating water, and 1-5 
per cent. to the hot plate, as an average for commercial 
ranges. These figures were very largely increased 
in appliances designed during the tests. It has been 
stated that market conditions preclude the com- 
mercial success of many improved types of range. 

Diseases of Plants in 
England in 1920-21." 
By Dr. E. J. Burrer, C.LE. 
OST countries in the civilised world have been 
forced within the last twenty years to take 
steps to protect their crops from the menace of foreign 
parasites. During that period, with the growing 
recognition of the aid that science can give to agri- 
culture by studying the cause and control of plant 
diseases and pests, has come a great increase in 
knowledge of the dangers of unrestricted traffic in 
plants. Many instances have occurred to prove how 
real is the risk of introducing plant parasites from 
other countries and how difficult to guard against. 
America has been the chief sufferer, but it is sufficient 
to mention gooseberry mildew and wart diseases of 
potato to show that England has not escaped. 
Distances, as measured in time and in the amenities 
of transport, are constantly contracting between the 
continents, and the interchange of living plants— 
with their parasites—goes on in ever-increasing 
volume. Quarantine restrictions, at first imposed in 
a few special cases, have extended until at present 
the exporting seedsman or nurseryman is faced with 
barriers to his trade which are often extremely 
hampering. It is easier for a human being to enter 
the United States to-day than for a potato, unless it 
is accompanied by a sheaf of health certificates ; while 
total prohibition of certain categories of plants is 
not uncommon. 
Correspondingly heavy responsibilities have fallen 
on the official plant pathologists of the various 

1 Ministry of Agriculture and Fisheries. Report on the Occurrence of 
Fungus, Bacterial and Allied Diseases on Crops in England and Wales for 
the years 1920-21. (Miscellaneous Publications, No. 38.) Pp. 104. 
(London: H.M. Stationery Office, 1922.) 35. net. 
NO. 2786, VOL. TIT] 
countries. Produce for export has to be inspected 
and certified, and imports from each country have to 
be scrutinised for possible dangers. As an essential 
foundation for efficiency in what may be called the 
“Plant Protection Service,’’ it is obviously necessary 
to know what diseases already exist in one’s own 
country and what may be introduced from each of 
the countries from which imports are received. 
Plant disease surveys have been developed in nearly 
all the more advanced countries, that of the United 
-States being the most complete, as is natural in view 
of the vast interests involved. So far as the fungous 
diseases are concerned, it is to Mr. A. D. Cotton, 
mycologist to the Ministry of Agriculture, that is 
due the organisation of the English survey. The 
present report is the third of the series for which 
he has been responsible, and will be the last in_view 
of his appointment as keeper of the Herbarium, Royal 
Botanic Gardens, Kew. It is also by far the most 
complete that has yet appeared and is second to none 
in any European country. 
Thereport covers the twoyears tg2z0and1921. These 
years offered an extreme contrast in their meteoro- 
logical features, and not the least valuable of the 
results of the survey is the way in which the differences 
in the two seasons are reflected in the incidence of 
particular diseases. Potato blight, a lover of cool 
and damp conditions, was rampant in 1920, but 
could not withstand the hot, dry summer of 1921. 
The attack of crown rust on oats in Wales was un- 
precedented in the former year and singularly slight 
in 1921. The mildews, on the other hand, were 
unusually bad in 1921, and common scab of potatoes, 
a a i Nl li al cite Bi as 


