362 



NATURE 



{_March 7, 1878 



incredibly short space of time the stanchions and guard- 

 rails were flung down, the water-tight doors closed, and 

 the couple of Gatling guns dismounted from their carriages 

 on the superstructure deck and hoisted up to the 

 tops, whence they could each discharge 2co shots per 

 minute upon hostile boats. Presently the process of 

 loading the guns was gone through, in the fore turret by 

 hydraulic power, and in the after turret by hand gear ; the 

 turrets were rotated and the guns run out, and the 

 snapping of the tube fuses told the spectators that a 

 furious action had commenced. 



The party was next conveyed to the Vertion, torpedo 

 school, where Capt. Arthur and Commander Wilson had 

 still more surprising wonders in the art of warfare for 

 them to witness. First of all. Commander Wilson deli- 

 vered a hurried lecture on the mysteries of torpedo science, 

 explaining the differences between offensive and defensive 

 torpedo warfare, the nature of the several explosive sub- 

 stances used, and the methods of firing torpedoes — me- 

 chanically, by means of glass tubes of sulphuric acid, 

 which explode on coming in contact with chloride of 

 potash, or glass tubes filled with potassium, which causes 

 explosion on mixing with the water, or, electrically, by 

 means of detonation produced by fulminate of mercury. 

 Commander Wilson also showed by means of a model in a 

 tank the method of ascertaining when a ship is over a 

 sunken torpedo by means of cross-bearings, and how the 

 mine is fired as soon as the telescope which is following 

 the movements of the ship completes the electrical circuit. 

 As the model, however, did not sink with great alacrity in 

 its mimic ocean, Commander Wilson explained that the 

 torpedo did not profess to destroy a ship instantly, but 

 only to knock a hole in the bottom about the size of a 

 barn door. At the conclusion of the lecture the company 

 again went on deck, and saw discs of dry and damp gun- 

 cotton harmlessly consumed, and how a solid block of wood 

 could be shivered by the same material when exploded with 

 a detonator. Next, on looking over the bulwarks, they 

 beheld a practical illustration of the boat's crew " creep- 

 ing" for an enemy's torpedo, the process consisting in 

 dragging for the mooring chains, and, when found, 

 destroying them by a discharge of gun-cotton. They 

 were also shown the manner of attack with star tor- 

 pedoes, firing lines of counter mines by "bumping" the 

 circuit closer, and, lastly, how attacking boats can be 

 destroyed by grenades fired by fuses held in the hand. 

 These beautiful experiments closed the day's programme. 

 We are glad that so large a body of our legislators 

 were present, and we are sure they could not fail to be im- 

 pressed with the importance of science in its bearing on 

 war. In fact it has become clear that the more war we 

 have, or are likely to have, the more is science needed ; 

 and it would indeed be a very short-sighted policy for 

 Government to cut down the very moderate supplies 

 allowed to science for the purpose of providing war 

 expenditure. We hope that after what they saw on 

 Saturday the members of the House of Commons will 

 have a higher opinion of the national value of scientific 

 research than to adopt any such course. 



METEOROLOGICAL NOTES 



Tornado in Chester County, Penn,, U.S. — Mr. 

 Richard Darlington, of Ercildoun Seminary, has pub- 

 lished an account of a remarkable tornado which swept 

 over this portion of the United States on Sunday, July i, 

 1877. The tornado appears to have been first felt a little 

 to westward of the boundary iine between Chester and 

 Lancaster Counties, and to have thence run a course of 

 twenty-two miles, first in a direction E. 20° S., then E. 15° 

 S., and lastly, E. 7° S., moving bodily onwards at rates of 

 from five to fifteen miles an hour, the average progressive 

 movement being twelve miles an hour. The destruction of 

 trees, houses, and other property is estimated at about 



40,000 dols., the destruction being most complete in those 

 cases where the tornado moved across a valley. An 

 uninterrupted roar, like that of thunder, accompanied it 

 during its whole course, which is sufficiently accounted 

 for by the inherent energy of the tempest itself and the 

 havoc it wrought throughout its course, such as twisting 

 thick oak-trunks in two, tearing up tall trees by the roots, 

 and whirling them aloft, and blowing down buildings and 

 scattering their contents in all directions. The breadth 

 of the tornado varied from 100 to 300 feet, the average 

 being 200 feet, though the debris was scattered to a greater 

 distance on either side. It appears to have originated 

 between a south-west and a north-west wind, where a large 

 dark cloud seemed to form in the atmosphere, suspended 

 from which was a whitish funnel-shaped cloud whirling 

 round in a terrible manner. The air was thick with the 

 objects which were whirled aloft, the movements of which 

 closely resembled buzzards sailing round. The rotary move- 

 ment was to the left, and the cone appeared to be a cloud 

 of vapour nearly white, connected at the upper end with 

 a smooth surface of cloud somewhat darker. The upper 

 portion of the cone appeared to move in a straight line 

 and at a uniform rate, while the tail or lower end frequently 

 bent in different directions, as if swayed from its true course 

 by the hills and valleys it crossed. No rain fell in its 

 track, but hailstones of a large size and in great quantity 

 fell at intervals along its north side. Trees in the northern 

 half of the track were generally thrown down with their 

 tops to the south, while those on the southern side were 

 thrown to the north ; but at certain points, such as at 

 Ercildoun, trees and other debris were thrown down in 

 what appeared to be inextricable confusion. Some of the 

 observers state that the debris ascended up the centre of 

 the funnel-shaped cloud and fell back to the ground outside 

 it, but the tornado was too sudden, brief, and appalling to 

 admit of careful observations being made on this point, 

 which is all-important in its bearing on the theory of 

 tornadoes. No tornado is known previously to have 

 traversed this part of the United States. 



The Law and Origin of Thunderstorms. — In the 

 Christmas issue of the Bidletiii International of the Paris 

 Observatory, there is an interesting note on this subject 

 by Prof. Ch. V. Zenger, of Prague. He has examined 

 the thunderstorms which occurred at Prague during the 

 ten years ending 1849, and those at Vienna during the 

 four years ending 1875, arranging the dates of their occur- 

 rence according to the semi-solar days each period of 

 observation embraced, there being twenty-nine such semi- 

 solar days in each year. The general result is that, 

 dividing the semi-solar day into three equal portions, 

 47 per cent, of the whole thunderstorms occurred in one 

 of these portions, 32 per cent, in another, while only 21 

 per cent, occurred in the third. Prof. Zenger is of opinion 

 that this result points to a cosmical origin for the 

 thunderstorm, operating, no doubt, on pre-existing ter- 

 restrial conditions, an opinion which receiv.es some 

 countenance from the relation subsisting between thun- 

 derstorms and auroral and magnetic perturbations. The 

 subject is of sufficient importance to call for a wider and 

 more exhaustive treatment. 



Monthly Meteorological Bulletin of the 

 MoNTSOURTS Observatory, No. 69. — This number 

 gives the observations for August last, which now include, 

 for the first time, the hourly velocities of the wind in 

 addition to the hourly temperatures and rainfall, which 

 were added some months ago. The daily minimum 

 velocity of the wind, 7*2 miles per hour, for August occurred 

 about 6. A.M., and the maximum velocity, I3'i miles per 

 hour, about 2 P.M., the increase in the wind's velocity 

 being thus nearly doubled between these hours. These 

 hours are all but coincident with the hours of mean 

 minimum and maximum temperature. The table of the 

 hourly amounts of the rainfall is a peculiarly valuable 

 one. Several years must, however, elapse before its full 



