192 



NATURE 



[August 10, 191 1 



Is The Agricultural Journal of India (vol. vi., part ii.) 

 Mr. Keatinge continues his account of the rural economy 

 of the Bombay Deccan, dealing now more particularly with 

 capital. A high rate of interest prevails for several 

 reasons : capital is scarce in the country, and there is no 

 organisation enabling the cultivator to get into touch with 

 the money markets of the towns ; security is not always 

 good, and the money-lender incurs some social odium. In 

 consequence, a man raising a mortgage on good land has 

 even in favourable circumstances to pay 9 per cent, 

 interest, while in less favourable circumstances he may 

 have to pay up to 24 per cent., and on personal security 

 the rates go up to 100 per cent. There are two papers on 

 cotton, one by Mr. G. S. Henderson on the exotic 

 cottons in Sind, and one by Mr. P. Venkayya on the 

 Cambodia cotton, a hardy long-stapled annual, yielding 

 lint of a superior white colour. An interesting summary 

 of the cotton investigations now in hand by the United 

 Provinces Department of Agriculture is given by Messrs. 

 H. M. Leake and A. E. Parr in part i. of the same 

 journal ; these fall under two headings, the production of 

 an improved type or types suited to the conditions of the 

 Provinces, and their introduction into general cultivation. 



The growing importance of the Suez Canal is shown 

 bv a Parliamentary paper recently issued, which gives the 

 return of the shipping passing through the canal for the 

 vears 1908, 1909, and 1910. The net tonnage of the past 

 vear shows an increase of nearly three million tons as 

 compared with 1908. The gross receipts in 1910 were the 

 largest reached. The percentage of the British vessels 

 amounted to 62-9 as compared to those of all other 

 nations, Germany being second with 15-5 per cent., both 

 showing an increase over previous years, while the remain- 

 ing 21.6 per cent., representing all other nations, remain 

 practically at the same rate. 



The annual report of the conservator of the River Mersey 

 shows that since the commencement of the dredging and 

 deepening of the bar at the mouth of the river upwards 

 of 161 million tons of sand have been removed, the 

 quantity for last year being iS^ million tons. The 

 minimum depth of water maintained in the centre 

 of the dredged channel is 30 feet 3 inches. Dredgers are 

 now being employed in deepening the channel off the 

 Askew Spit, the revetment on the south side of Taylor's 

 Bank having been completed in November last. The 

 report also states that during 1910 nearly two million tons 

 of silt were dredged from the channel of the Manchester 

 Ship Canal, the whole of which would have found its way 

 into the estuary of the Mersey had not the canal works 

 interposed. 



Four years ago a scheme of irrigation was inaugurated 

 for supplying water for agricultural purposes in a district 

 in Canada near Calgary. The area of the district to be 

 irrigated covers three million acres, and involves the con- 

 struction of 4500 miles of canal, of which 1500 miles have 

 now been completed. The main canal is 17 miles in 

 length and 120 feet wide at the water-level, and is sup- 

 plied from the Bow River. Storage is provided by a 

 reservoir 3 miles long by half a mile wide, with a depth 

 of 40 feet. The total cost of the whole work is estimated 

 at three million pounds. In other parts of Canada also 

 extensive irrigation works are in progress, notably in the 

 fruit districts of Columbia. In this district the rainfall 

 ranges only from 9 to 10 inches as a maximum, falling 

 to as little as 2 inches in dry seasons. Without irrigation 

 the land in this dry district would be worthless. The 

 NO. 2l8o, VOL. Sj] 



area of Canada which is being opened up for fruit farm- 

 ing by irrigation extends over 30,000 acres. 



Communication No. 122 from the physical laboraton of 

 the University of Leyden contains a paper by Prof. 

 Kamerlingh Onnes on the disappearance of the electri. a I 

 resistance of mercury at the very low temperatures 

 obtained when liquid helium boils under reduced pr<". 

 The resistance of the mercury filament in the liquid 

 at o° C. was 173 ohms ; in the solid state at the same 

 temperature it would, if its temperature coefficient of 

 resistance remained constant, have a resistance of 40 ohm-. 

 At 3 absolute its resistance had sunk below 3X10- 6 

 ohms, that is to say, one ten-millionth of its resistant 

 o° C. The resistance of constantin (eureka) remained 

 nearly constant over the same range of temperature. In 

 a second paper Prof. Onnes and Mr. A. Perrier show that 

 paramagnetic and diamagnetic substances the magnetic 

 susceptibilities of which at ordinary temperatures 

 inversely as the absolute temperature at these very low 

 temperatures, deviate considerably from Curie's law. 



In the Bulletin for 1910 of the International Associa- 

 tion for Promoting the Study of Quaternions and Alii' d 

 Systems of Mathematics, in addition to the usual list of 

 members and the additions to the bibliography during the 

 preceding year, there are some reviews by Prof. J. Birnie 

 Shaw, the secretary. The most important is the critical 

 examination of Burali-Forti and Marcolongo's books cm 

 their new notation for vector analysis. Prof. A. Macfar- 

 lane, the president, communicates a short address, followed 

 by a paper on the unification and development of the 

 principles of the algebra of space. Here the author g 

 a well-arranged argument in favour of his system of what 

 might be called versorial analysis. He corrects Hamilton's 

 view of the quaternion exponential, and develops what is 

 undoubtedly a self-consistent system, in which the square 

 of the vector is kept positive, and associative flexibility 

 is obtained by the introduction of the imaginary. Com- 

 plexities of an unexpected kind seem to spring out of his 

 method, but as a piece of analytical reasoning it is of 

 great interest. No illustrations are given of the pra 

 value of the method. 



A small self-contained machine for the grinding and 

 polishing of metal specimens for microscopic examination 

 has been brought out by Messrs. R. and J. Beck, Ltd., 

 and the apparatus possesses certain advantages which 

 should render it particularly useful to metallurgists. The 

 whole machine is carried on a small iron bed-plate, and 

 consists essentially of a small enclosed electric motor of a 

 substantial type and the polishing spindle proper ; the 

 motor drives a counter-shaft, and from this the drive is 

 by a range of three-speed pulleys to the polishing spindle. 

 The polishing discs themselves are detachable from the 

 spindle, and run in a carefully designed casing, which not 

 only serves to catch the spent polishing materials, water, 

 &c, but also serves as a rest to the hand of the operator, 

 and in an emergency saves the specimen from injury if it 

 should accidentally escape from the operator's fingers. 

 The attachment of the polishing cloth to the discs takes 

 the somewhat novel form of a fairly stiff steel spiral spring 

 acting as a species of garter, and, provided that the spring 

 is strong enough to resist the centrifugal action at high 

 speeds, this forms a most convenient form of attachment 

 for both cloths and papers. With the addition of a suit- 

 able rheostat for controlling the speed of the motor, the 

 machine should prove equal to all requirements for metal- 

 lurgical polishing, although the use of separate machir.es 



