June 30, 19 10] 



NATURE 



change in the position of the observer between the two 

 readings, necessary in the older form of level, is almost 

 certain to cause some shift in the position of the bubble. 

 The staff is graduated on one face only, while the telescope 

 diaphragm carries three horizontal wires instead of the 

 usual single one. The two outside wires are equidistant 

 from the centre one, and in making an observation all 

 three wires are read. The necessity of having a second 

 set of staff graduations on another face with a different 

 zero and in different units is thus obviated, while the three 

 readings form at least as effective a check against errors, 

 and are more rapidly performed than the two required on 

 the older system. The American instrument presents the 

 additional advantage that the interval, as read on the 

 staff, between the wires gives a measure of the distance 

 of the staff from the observer. As an illustration of the 

 precision of which levelling is now capable we may take 

 the Bombay-Madras line. The length of this line is 806 

 miles, and the closing error was 0-607 foot, or about 

 i/ioo inch per mile. A closeh' comparable figure could 

 be derived from other lines. Taking another test of 

 precision, viz. the difference in the results of two observers 

 each making a single traverse of the same line, we arrive 

 at a figure of about 1/20 inch per mile. 



In our issue of December 23 last we briefly alluded to 

 an interesting paper, by Mr. W. G. Reed, jun., on South 

 American rainfall types, recently read before the Royal 

 Meteorological Society. The author constructed a map of 

 very large size, making use of all published data, and from 

 an inspection of the curves it was seen that (generally 

 speaking) there is a marked division of the rainfall into 

 the following five types : — (i) double maximum, including 

 the region north of the Amazon and west of Dutch Guiana ; 

 (2) maximum early in the year, including Guiana and the 

 northern part of Brazil, except the coast region ; (3) winter 

 maximum, in the northern coast States of Brazil, also on 

 the west side of the continent south of the equator and 

 west of the Cordillera ; (4) summer maximum, extending 

 over central and southern Brazil, Bolivia and Paraguay, 

 and as far south as Buenos Aires ; (5) rain at all seasons, 

 embracing the southernmost States of Brazil, Uruguay, 

 south of Buenos Aires, and east of the Cordillera. Small 

 graphs are drawn for stations exhibiting general types of 

 the annual range of rainfall applicable to each of the large 

 divisions. The author also compares his own map of 

 seasonal rainfall with those previously published, prefer- 

 ence being given to that b\' E. L. Voss contained in Peier- 

 maitn's Mitteilungen, 1907. 



The Univcrsit}' of Wisconsin has issued an account of 

 some instructive experiments on manuring which, while 

 not new in principle, will be of value to agricultural 

 lecturers. The sand}- soils of northern Wisconsin are 

 deficient in humus and in nitrogen, both of which could 

 be applied as dung or purchased organic fertilisers. It is, 

 however, much cheaper, and distinctly more effective, to 

 grow a crop of clover on the soil during the previous jear, 

 and then to plough it in. The New Mexico Agricultural 

 College has published a bulletin describing the methods of 

 apple culture under irrigation. Apples will grow in a 

 great variety of circumstances, and can be produced in 

 regions lying outside the old apple belt if methods like 

 irrigation are adopted. 



The Electrician for June 10 contains a supplement of 160 

 pages devoted to the applications of electricit}- to marine 

 work. Already a large proportion of the auxiliary power 

 required on a modern liner or battleship is supplied elec- 

 trically, but the electrical engineer looks forward to the 



NO. 2X22, VOL. 83] 



near future when electricity will play an important part 

 in the propulsion of vessels. Three possible systems of 

 electro-mechanical propulsion are described in this supple- 

 ment. In each the prime mover is coupled direct to one 

 or more dynamos, which in turn drive motors on the screw 

 shafts. The great flexibility of the electrical method of 

 transmission makes it possible to vary the speed of the 

 ! vessel between wide limits without running the machinery 

 at low efficiency. The question of the prime mover of the 

 future is obviously an important one, and several of the 

 writers of the articles expect the oil engine to displace the 

 turbine, just as the turbine has displaced, or rather is dis- 

 placing, the reciprocating steam engine. 



A NEW petrol-electric motor omnibus, constructed by the 

 Daimler Company, is illustrated in the Engineer for 

 June 24. Two power units are fitted, one at each side 

 of the frame under the seat line, each capable of develop- 

 ing 12 horse-power. The engines are of the new Daimler 

 type, with crank shafts and frames extended for the 

 dynamotors, by which term is meant an ordinary con- 

 tinuous-current dynamo which is also used as a motor. 

 Each dynamotor is normally rated at 3 kilowatts, but has 

 a give-and-take capacity of three to four times this rating. 

 It is stated that on ordinary greasy roads it is found 

 almost impossible to cause this new omnibus to skid or 

 side-slip to any appreciable degree, and nothing in the 

 nature of a dangerous side-slip has been experienced in 

 5000 miles' driving. This immunitj- is attributed to the 

 following factors : — the extreme flexibility of the double- 

 unit system ; the better weight distribution obtainable by 

 the construction adopted ; the distribution of braking over 

 the front and rear wheels, and the improved methods of 

 braking employed ; the improved co-axial pivot steering ; 

 and the comparative absence of unsprung weight. The 

 total weight of the vehicle, complete and ready for running, 

 is 3 tons 9 cwt., the regulations allowing 3 tons 10 cwt. 



OUR ASTRONOMICAL COLUMN. 



Meteorite at Bombay. — Mr. W. F. Denning writes : — 

 " .Advices from India mention the fall of a brilliant fire- 

 ball at Bombay on the afternoon of .\pril 25 last, at 4.15 

 (standard time). One observer says the meteor flashed out 

 three times in a descent nearly vertical, and the appear- 

 ance suggested huge drops of fire from a Roman candle. 

 .\ few minutes later there was a report as loud as one of 

 the harbour guns, only more muffled, and the impression 

 was that a big mine had exploded in the neighbourhood of 

 Khandalla. 



" At Lauovli a loud rumbling sound startled the in- 

 habitants, the houses being shaken. Looking upward, 

 people saw a long thin line of smoke rolling from the 

 S.^^'. to N.E. across the sky. Further reports indicate 

 that the fiery ball shot up from the direction of the sun. 



" Other observers at Bombay say that the detonation 

 resembled a blasting operation, heard for many miles 

 around, and lasting nearly a minute. The meteor appeared 

 as a white-hot ball, and it left a long, luminous trail. On 

 striking the surface of the Bombay Harbour it threw up 

 a high column of water with steam. 



" At Khandalla a terrific noise was heard proceeding 

 from the direction of Poona. 



"It is doubtful whether the object really descended in 

 Bombay Harbour, as one observer says, though it gave 

 that impression, }-et it evidently fell far beyond that spot. 

 Directed from the S.E. sky, the radiant was probably in 

 Leo, but the height of the meteor cannot be preciselv ascer- 

 tained from the data available. This is the third brilliant 

 meteor seen in sunshine during the last nine months. 

 Others were reported in England on October 6, 1909, and 

 May 10, 1910. 



" The region of Leo seems to be a prominent one for 

 the supply of unusual meteors." 



