592 



NA rURE 



[April ?4, 1902 



canal schemes in Central America. The probable traffic of a 

 canal, when constructed, is analysed, and its chance in competi- 

 tion with North American railways estimated. 



The first place in the April number of the Geographical 

 Journal is given to a series of three papers on the voyage 

 southward of the Discovery, by Dr. H. R. Mill, .Mr. George 

 Murray, and Sir Clements Markham. Dr. Mill describes the 

 equipment and routine work on board in meteorology and 

 oceanography, and gives an account of his week's voyage to 

 Madeira. Mr. Murray's paper continues the voyage from 

 Madeira to the Cape, but it is chiefly occupied with an 

 interesting account of a landing expedition on South Trinidad, 

 an oceanic islet the name of which is familiar to readers of the 

 "Cruise of the Falcon." Sir Clements Markham describes, 

 from reports which have been sent home, the experiences of the 

 Discovery from the lime of leaving Cape Town until her final 

 departure from Lyttellon for the Antarctic. During the east- 

 ward voyage, the Discoverymet with exceptionally heavy weather 

 and acquitted herself well, showing that so far as sea-going 

 qualities are concerned her design leaves nothing to be 

 desired, while the constructional defects developed, and partly 



made good in dock at Lyttelton, are not such as to cause 

 apprehension of any kind. The chief features of the 

 voyage were an excursion to lat. 63° S. in long. 140 E. — with 

 the double object of observing the change of magnetic force 

 along the agonic line, and of giving the ship and her crew a 

 first taste of the ice— and a visit to Macquarie Island, where 

 valuable collections were made. In conclusion. Sir Clements 

 Markham describes the arrangements in progress for sending 

 out a relief ship next June. A Norwegian whaler, ihe- Morning, 

 of Tonsberg, has already been purchased, but more funds are 

 urgently needed for her proper equipment and dispatch. The 

 photograph we reproduce from the y<?«)'«a/ shows the Discovery's 

 departure from Lyttelton. 



The United States Weather Bureau has published a discus- 

 sion of the oss of life in the United States by lightning {Bulletin 

 No. 30). The inquiry was begun in 1890, and has therefore 

 extended over eleven years. The number of persons killed 

 during 19CX) was "13; of this number 291 were killed in the 

 open, 158 in houses and 57 under trees. In the same year, 973 

 NO. 1695, VOL. 65] 



persons were injured ; of these 327 were in houses, 243 in the 

 open and 29 under trees. During the eleven years 1890- 19CX), 

 the average number of persons killed yearly was 377. The 

 greatest mortality by lightning, considering both unit area and 

 density of population, is in the Ohio \'alley and the Middle 

 Atlantic States; but if density of population only be considered, 

 it is in the Upper Missouri Valley and middle Rocky Mountain 

 region. The great majority of storms occur in the summer 

 season, but winter thunderstorms are not infrequent in the (julf 

 States and occasionally extend e.tstward along the Atlantic 

 coast to Massachusetts. The Bulletin has been prepared by 

 Prof. A. J. Henry, and contains some useful rules to be observed 

 during thunderstorms and on the treatment of persons struck by 

 lightning, even though they may be apparently dead. 



Mkssks. a. Gali.enkamp and Co., the London agents 01 

 a well-known firm of opticians of Zilrich, have lately introduced 

 to our notice two very handy and efl'ective little instruments for 

 obtaining the dew-point and humidity of the atmosphere with- 

 out the necessity of calculating the different hygrometric values 

 by means of the usual tables. One of the instruments, 

 Lambrecht's polymeter, so-called from its showing several con- 

 ditions, is a combination of the thermo- 

 meter and hair-hygrometer, each provided 

 with two scales, showing temperature in 

 Fahrenheit degrees, elastic force of vapour 

 in millimetres (or weight of vapour in 

 grammes), the relative humidity and 

 "number of degree," or the difference 

 between the dew-point and the tempera- 

 ture of the air. For showing the tem- 

 per.iture of the dew-point independently 

 (if desired) a neat little instrument is 

 iiseil, consisting of a drum, to which a 

 tliermometer and polished disc are at- 

 lached ; a small quantity of ether is intro- 

 duced into the drum and brought into 

 contact with the bulb of the thermometer 

 by forcing air into the drum by a very 

 simple contrivance; as soon as the de- 

 position appears on the disc, the tempera- 

 ture of the dew-point is indicated by the 

 thermometer. The chief feature of these 

 instruments is their portability and the 

 f.icility with which they can be used. 

 Both instruments will be found valuable in 

 connection with questions of health and in 

 certain industries which are affected by 

 moisture ; also for the prediction of weather, so far as it 

 depends on the same cause. For the latter purpose a series 

 of rules has been compiled by Dr. A. Troska. 



It was remarked by Laplace that when a liquid is free to rise 

 in a capillary tube there may be several positions of equilibrium 

 if the .section is not uniform, and, moreover, that from general 

 dynamical grounds positions of stable and unstable equilibrium 

 follow each other alternately. A fuller investigation of this 

 problem is now given bySignor (i. Morera in a note contributed 

 to the Atti ih-i Liiuei, xi. 6. The author obtains, from mathe 

 matical considerations, a curve the intersections of which with the 

 meridian section of the tube determine the positions of equili- 

 brium. If in ascending the curve passes from the outside to the 

 inside of the tube, the corresponding position of equilibrium is 

 stable ; if the contrary is the case, the position is unstable. Of 

 course an exceptional case of what is sometimes called "stable- 

 unstable " equilibrium occurs when Signor Morera's curve 

 touches the meridian section of the tube. In the investigation 

 it is assumed that the interior surface of the tube is a figure 



