Vol. XVIII No. 452. 



THE AGRICULTURAL NEWS, 



265 



controlling the disease by serum treatment A full 

 account of hog cholera or swine fever will be found in 

 the West Indian BaWiin, Vol. XVII, No. 3. The 

 trouble is, however, that there is more than one disease 

 which may be confused with swine fever. This makes 

 diagnosis difficult, and specific treatment uncertain. 

 For instance, there is hemorrhas^ic septicannia or 

 swine plague. It is very difficult to distinguish swine 

 plague from hog cholera. H. J. Washburn in 

 Farmers Bulletin, No. 10 18, United Soates Depart- 

 ment of Agriculture, states : ' the two diseases maj' 

 actually occur in the same animal. Should the out- 

 break seem to be but slightly contagious, and not 

 inclined to spread from the premises upon which it 

 first appeared, it is probably not hog cholera, but if it 

 spreads rapidly throughout the neighbourhood, it is 

 undoubtedly due to hog cholera infection. The 

 presence of the characteristic bacilli does not alone 

 establish a diagnosis of swine plague, since those 

 organisms are found frequently as secondary invaders 

 in true cases of hog cholera, and again tbey are ofi en 

 present in the noses or throats of healthy swine.' 

 Outbreaks of contagious diseases in swine, there- 

 fore, require very careful investigation. Those people 

 who are concerned with pig raising in the iropics 

 would do well to obtain information as to the methods 

 adopted in Cuba, where hog raising has now reached 

 large proportions, and has attained to a high degree 



of efficiency. 



■ I ^ — • 



Soil Deficiencies. 



In articles which have appeared in previous 

 issues of the Ayr iculturnl News during the present 

 year it has been pointed out that the deterioration in 

 the yield of crops is very often primarily due lo the 

 conditions of soil, more than to attacks of insect or 

 fungus enemies, which may be considered rather as a 

 sequel to soil defi iencies. For instance, it has been 

 pointed out by Mr. W. Nowell that probably the best 

 means of combating the froghopper pest of the sugar- 

 cane will be to pay more attention to the condition 

 of the soil. The late Mr. Farquhareon of Nigeria 

 also emphasized the necessity of improved cultivation 

 for the well-being of the cacao cultivation in West 

 Africa. 



A paper r« cently read by Professor H. E. Armstrong 

 at a meeting of the Society of Arts dealt with the 

 subject of soil deficiencies in India. In the course of 

 his paper Professor Armstrong laid stress on the effect 

 which the deficiency of any one ingredient in the soil 

 necessary to the health of a plant may have upon its 

 life. With regard to phosphorus for instance, and its 

 frequent deficiency in tropical soils, his remarks are 

 worth attention by all interested in tropical agricul- 

 ture. 



As an instance of how the supply of this ingredient 

 to soil deficient in it has led to great results, Professor 

 Armstrong adduces the case of some lauds in Australia, 

 on which, after clearing, it was found impossible to 

 grow wheat, but the application of a sma I amount of 

 phosphatic manure led to productive crops of ih;s cen al. 



With regard to tropical cultivation, Professor 

 Armstrong ii of the opinion that the forced abandonment 



of coffee cultivation in Ceylon may have been really 

 due to soil deficiency, which enfeebled the plants, 

 rendering them an easy prey to the attacks of the leaf 

 fungus. He goes on to utter a warning that what hap- 

 pened to coffee in Ceylon may possibly well happen te 

 rubber, not only in that island, but in other places. 



It seems to be worth while for planters of other 

 tropical crops, such as limes for instance in the West 

 Indies, carefully to investigate the conditions of their 

 soils, with a view to supplying any ingredient 

 lacking in them necessary for the proper develop- 

 ment of the particular crop cultivated. In this 

 direction the scientific assistance of the various agri- 

 cultural departments will surely be readily available, if. 

 sought for. 



-^^•-♦-^ 



The Aeroplane for Surveying. 



The Director of the United States Coast and 

 Geodetic Survey has written an article to Science 

 (.June 20) on the coming use of the aeroplane (or 

 airplane, as it is spelt in America) for purposes of 

 surveying and mapping. The principal application 

 will be fur photographic purposes. It will be possible 

 to make very rapid .siuveys of interior tracts of coun- 

 try by means of aerial photography, and to show 

 accurately and in detail the position of every, 

 topographical feature. Much has been done during 

 the war to advance aerial photography, and the 

 possibilities it offers for geographical work in peace 

 time will cause the advancement to be energeticilly 

 pros'Cuted Research concentrated on the camera, 

 rather than on the aeroplane or airship seems to be 

 what is most urgently required. Sopie method of 

 ensuring that the camera is perfectly vertical at the 

 time of exposure will be necessary : that is, a inethod 

 of regulating tilt, for tilt has the effect of causing 

 distortion. 



Aerial survey will be of immense value in the 

 agricultural development of such territories as British 

 Guiana, British Honduras, and the great African 

 possessions. With greater perfection of the camera 

 it should be posgible to illustrate the vegetative 

 characteristics of a country from an airship at low 

 altitudes. Possibly also cinematograph films could 

 be taken. 



Another use of aerial photography will be for the 

 location of dangers to navigation. Altogether, the use 

 of airplanes for survey work offers immense possibilities, 

 as it also does for communication between inaccessible 

 places. It is a matter for surprise that no attempt is' 

 being made to introduce aerial transport and survey 

 work into the great tropical territories, which contain 

 abundant resources to repay at no distant date the 

 initial expenses incurred. 



Since the above was written, a recent issue of the/ 

 Journal of the Hoi/al Geographical Society (for June) 

 has come to hand containing a most valuable paper 

 on mapping from air photographs by Lieut.-Col. 

 Macleod, D.SO., R E. This paper, which is illustrated- 

 with remarkably fine plates, shows that in the subject)' 

 dealt with great progress has been made in England. 

 It would seem that the American writer is nob' 

 familiar with this progress. 



