60 The N.Z. Journal of Science and Technology. [Jan. 
An Atlas oi the World’s Agriculture. 
Among the many activities started in America since the entry of the 
United States into the war has been the collection into a convenient form 
of the scientific knowledge useful for the troops in France, such as Professor 
Davis’s geological Handbook of Northern France, and more generally educa¬ 
tive work concerning the bearing of the great struggle upon economics. 
Among these has recently been issued by the United States Department of 
Agriculture The Geography of the World’s Agriculture, “ a small by-product 
of the atlas work called forth by the foreign situation.” This consists of 
over two hundred diagrams, with explanatory text, showing the distribution 
of all types of agriculture, charted on a basis of the statistics of 1912. Each 
country has been divided into as small areas as the information permits, and 
the charts drawn representing the production of any commodity—quantity, 
value, or acreage—are shaded with dots, each dot properly placed indicating 
a certain unit quantity produced within a given area. The general shade 
produced thus shows very vividly the intensity of productiveness. Of 
special interest in this part of the world are the charts illustrating the number 
and distribution of sheep and of cattle in Australia and New Zealand, and 
of wheat-growing and vine-growing in Australia. We are also informed that 
though Australia leads the world in the total number of sheep in 1912 
(she has since fallen below the record set by the Argentine Republic) New 
Zealand ranks next to Uruguay and Turkey in the possession of the greatest 
number per square mile (and according to later statistics practically equals 
Uruguay in possessing the greatest number per head of population). Besides 
the immediate economic value of this compilation, it will be most useful 
in studies of the relation of climate and topography to production. 
W. N. B. 
The Latent Heat of Steam, by F. B. Aspinall. The Engineer, vol. 124, 
pp. 3-4, 25, 47-48, July 6, 13, and 20, 1917. 
An attempt by this author some years ago to find the “ missing 
quantity ” led to conclusions so radically opposed to the accepted 
doctrines, founded on Regnault’s experiments, that the late Dr. Silvanus 
Thompson brought the matter before the City and Guilds of London 
Institution for Technical Education. This body made a liberal grant to 
defray the cost of experiments carried out at Finsbury Technical College, 
and these articles are an epitome of the results. 
The apparatus used in the tests is described with praiseworthy care, 
and the method adopted consisted in measuring the total heat of slightly 
superheated steam and applying the necessary corrections. By this method 
the question of wetness of the steam was overcome, and it is to this fact 
that the author attributes the radical difference between his figures and 
those of Regnault. 
The conclusions arrived at were— 
(1.) The latent heat of steam is constant, its value being 970 B.Th.LT. 
(2.) Steam-volume multiplied by steam-pressure is - constant, the value, 
stated in cubic feet and pounds absolute, being PY = 400. 
(3.) Other determinations have been vitiated by the steam being wet 
or containing air. 
(4.) The missing quantity is a mathematical error due to erroneous 
values for volume and latent heat. 
