LAURIE, D. F. Department of Agriculture of South Australia, Bulletin No. 74. Adelaide, 1912. The poultry tick (Argas persicus, super family Ixodoidea, family Argasidae) was, according to the writer, introduced into South Australia from India and does much harm in the former country, being the means of transmitting Spirochaeta Marchouxi (the causative agent of tick fever). Good results against tick fever have been obtained with salvarsan, but the only radical cure, in the opinion of the writer, is the eradication of the tick. To this end Mr. Laurie has tried various measures and he finds that a 5 or 10 per cent. kerosene emulsion is the best remedy. The ticks are destroyed by one minute's immersion in this liquid; for practical purposes, the spraying, and even soaking, of poultry houses with this emulsion has proved efficacious. Old timber containing many cracks, which serve as shelters to the ticks, should not be used for poultry houses. The paper deals at length with the life-history of the insect and is illustrated with many good plates. It also gives the regulations in force in South Australia regarding the diseases of poultry. 398 Sacbrood, a Disease of Bees. WHITE, G. F. in U. S. Department of Agriculture, Bureau of Entomology, Circular No 169. The writer refers to the works of Howard, Maassen, Burri and Kürsteiner on brood diseases of bees. The last-named investigators found diseased brood free from bacteria in Switzerland. This disease was carefully studied by the writer, who gave it the name of " Sacbrood ". Brown is the most characteristic colour assumed by the infected larva during its decay. Various shades are observed; the term "gray" might sometimes be used to describe the colour. The form of larvae which have succumbed to this disease changes much less than it does in foul brood, and the body wall is, as a rule, not easily broken; thus often the entire larva can by removed intact from the cell. The content of this sack-like larva is more or less watery; the head end is usually turned markedly upwards. There is practically no odour from the brood combs. In the investigations of the disease, dead and infected larvae were picked from the combs, crushed, and mixed with sterile water. This suspension was filtered in a Berkefeld filter. The filtrate was fed in syrup to six healthy colonies and sacbrood with typical symptoms was produced in all the colonies thus fed. Filtrate from the brood of one of the artificially infected colonies, when fed to two healthy ones, produced sacbrood in each. Other experiments made indicate that the virus is killed by the application of a comparatively small amount of heat. The writer intends publishing a detailed account of his investigations. BEES FISH 399 Tape-Worm Disease of Roach and Bream. An investigation of the waterfowl which frequent the Müggelsee near Berlin has shown that the strap tape-worm (Ligula simplicissima), which is found sexually immature in roach and bream, occurs in large numbers, and with fully developed reproductive organs, in the alimentary canals of Common Gulls (Larus canus), Black-headed Gulls (L. ridibundus), Goosanders (Mergus merganser) and Red-breasted Mergansers (Mergus serrator). AGRICULTURAL AND IMPLEMENTS FARM ENGINEERING. 400 Comparison of Sources of Mechanical Power in Agriculture (1). SCHWANECKE, H. K. Vergleich mechanischer Betriebskraft im Landwirtschaftsbetricb. Fühlings Landwirtschaftliche Zeitung, Year 62, Part 3, pp. 95-108. Stuttgart, February 1, 1913. This paper compares, with the help of diagrams, the most important power machines used in farming, as regards the cost of installing and working them, the space, upkeep and assistance they require, as well as their safety and readiness for use. The total cost of installation of power machines increases naturally with their size, while at the same time the cost of installation per H. P. diminishes; but the different machines vary considerably in this respect. These differences are shown in the annexed diagrams (figs. 1 and 2). (2) It will be seen that electric motors require the least cost of installation, next follow combustion motors, then steam engines and lastly wind motors. Within these main lines there are smaller variations which are also clearly shown by the diagrams. The working expenses include generally interest and amortizement of installation capital, repairs and upkeep of the plant, fuel, lubricants, etc., and wages of engine men. To these must be added smaller sums for the insurance of the plant and attendants, etc. The interest and amortizement are in the main constant annual expenses, and nearly the same whether the machine works much or little, while the other expenses depend mostly upon the greater or less use of the plant. In figs. 3 and 4 the curves show the working expenses for 300 and for 600 hours' work per annum. As regards the amount of space required, the writer gives the following data: Electric motors require the least space, combustion motors follow, after which steam engines fixed and portable, gas motors and last of (1) See No. 829, B. May 1912. (Ed.). (2) The Mark is about 0.98 of a shilling; taking it as shilling, cach division in fig. 1 represents £100 and in fig. 2 £10. In fig. 3, each division (4 Pf.) represents very nearly one halfpenny. (Ed.). all the improved steam engines. Wind motors do not as a rule require much space, and local conditions decide as to the advantage of using them. The smallest demands as to upkeep and attendance are made by electric and wind motors. Combustion motors follow, after which come gas motors and then steam engines. The greatest safety in working and the greatest durability are afforded by electric motors and in general also by wind motors. Somewhat less favourable are the combustion and gas motors, and least of all the steam engines. Also as regards the ease and rapidity with which they may be set going, electric motors occupy the first place, followed, in decreasing order of merit, by combustion motors, gas motors and steam engines. Finally, the writer observes that the choice of the power machine depends very much upon local conditions and that consequently no particular group of motors may be considered absolutely superior to the others. 401 A New Dynamometer for Steam Ploughs. REZEK, J. Ueber ein neues Dampfpflug-Dynamometer. Mitteilungen der landwirtschaftlichen Lehrkanseln der k. k. Hochschule für Bodenkultur, Vol. 1, Part 3, pp. 393-406. Vienna, January 15, 1913. The writer draws attention first to the great difficulties which attend the technical investigations on the double engine system of ploughing, in determining the indicated power and that effectively transmitted from the engine to the plough, and then to the unreliable character of the instruments and methods hitherto employed for this object. After an exhaustive review of the existing dynamometers, the writer describes the solid and durable apparatus he has invented (figs. 1 and 2) and its perfect and reliable working. This belongs to the group of cylinder and piston instruments. Its cylinder, filled with glycerine, is connected with the draught hook of the plough and the piston with the cable of the working engine. The pressure exerted on the liquid is registered by an indicator, shown in the drawing, on a strip of paper fastened to a drum which is caused to revolve in the same direction by a belt from the axle of the bearing wheels. This cylinder and piston instrument has the advantage over spring dynamometers in having a rigid non-elastic connection between the motor and the working implement, thus in no way altering the manifestations of the work to be examined. It can besides be built of the necessary dimensions to ensure the required solidity and durability of the instrument, which is not possible with Prof. Giordano's box dynamometer (1), the principle of which requires the sides to be as thin as possible. A further advantage of all cylinder and piston instruments lies in the possibility of using with them steam engine indicators. While in box dynamometers the deformation of the box is constant, in cylinder and piston instruments there is a cause of error in the friction (1) See: GIORDANO FEDERIGO. Le ricerche sperimentalt di meccanica agraria, p. 132. Milano, 1906. (Author's note). |