April 13. 1893] 



NATURE 



573 



resistance of air alone, apart from the frictional resistances, 

 would not be less than 1700 horse power. Though there is 

 nothing to prevent the construction of electric locomotives cap- 

 able of developing this or even greater power, the strength of 

 the materials at present at command will set a limit to the speeds 

 which may be obtained. r .• r n 



In order that the engineer may realise the imperfection of all 

 his works, it is well for him to be constrained from time to time 

 to contemplate the amount of energy involved in his final pur- 

 pose compared with the energy of the coal with which he starts. 

 I have endeavoured to put before you to-night the losses that 

 occur and the reasons for them, in some steps of the complex 

 machine which constitutes an electric railway, so in conclusion 

 I will draw your attention to the ultimate efficiency of the 

 machine, starting with the coal and ending with the passenger 

 carried through space. The diagram on the wall, starting with 

 the familiar I2,cxx),ooo foot-pounds, the energy of a pound of 

 coal, shows the loss in each step, supposing it inade with the 

 most economical appliances known to the engineer, first in 

 the boiler, then in the steam engine, generator dynamo, con- 

 ductors, locomotives, in the dead weight of the train, till finally 

 we arrive at the energy expended on the passenger himself, 

 which we find to be 133,000 foot-pounds, or but little more than 

 I per cent, of the energy with which we started. It is true in- 

 deed that transportation is a more etonomical process than 

 lighting with incandescent lamps, in which the final efficiency is 

 about one-half percent., but whether in lighting or in traction, 

 when we consider that ninety-nine parts are now wasted for one 

 part saved, we may realise that the future has greater possibilities 

 than anything accomplished in the past. 



HAIL STORMS.' 



SOME recent thunder and hail storms were so violent that they 

 call for more than a passing notice, not only on account of 

 their severity, but also because they are well marked phenomena 

 in our weather. The district in which they were most severe is 

 that around Narrabri, and the weather map for the day indicated 

 this district as one in which storms would probably manifest great 

 intensity. The places from which the best accounts have reached 

 me are Narrabri, Avondale, thirty miles due north of Narra- 

 bri, and Tulcumbah, fifty-seven miles south-east of Narrabri. 



The Sydney weather chart at 9 a.m. on October 13, the da\ 

 of these storms, shows us that there was but little difference in 

 pressure all over Australia. To the west of the overland tele- 

 graph line it was slightly higher, over western New South Wales 

 and Queensland lower, and higher again over the East Coast, 

 in which the isobars clearly outline the area of relatively low 

 pressure, and the kinks in them indicate disturbed conditions, 

 local short-lived storms, and before the day was over the infer- 

 ence from the state of pressure was fully justified, for storms of 

 extreme violence occurred over the area; storms which swept down 

 great forest trees two and three feet in diameter. What this 

 means in wind velocity I am unable to say, the trees are eucalypts, 

 and therefore the wood is hard and very strong, but they were 

 treated as if they were reeds, and their strength was as nothing 

 compared with the force of the wind. 



These storms are common enough, but owing to the sparse 

 population they seldom pass over towns or dwellings. In this 

 instance such has been the case, and in the future as population 

 increases similar cases must increase in number, for the storms 

 are abundant, indeed these storms form a well-marked feature of 

 our summer weather. As a rule they are disconnected, and the 

 most violent part of the wind covers but two hundred or three 

 hundred yards wide, and travels along with great rapidity, leav- 

 ing a narrow line of destruction in its wake. 



On the day in question heavy storms were reported at Good- 

 ooga, Armidale, two hundred and forty miles south-east of 

 Goodooga, and at Grafton one hundred miles norih-east of Armi- 

 dale. Storms which seem to have been quite disconnected, for 

 the earliest time was at Grafton, and as a rule they come from 

 the west ; ihese are spoken of as severe storms, but were evidently 

 not specially remarkable, nothing to compare with those in the 

 Narrabri district to which I wish to direct your attention. Un- 

 fortunately, data for determining the rate of progress is not avail- 

 able, although that as to the intensity of the storms is abundant, 

 I may mention that three days before these storms, that is on 



1 Read by H. C. Russell, F.R.S. before the Royal Society of N.S. Wales, 

 November 2, 1892. 



NO. 1224, VOL. 47] 



October 10, a similar storm passed over from Wilcannia to- 

 Sydney, a distance of four hundred and eighty miles, at the 

 rate of fifty-five miles per hour ; and I have before traced one 

 over the same part of the colony, the rate being fifty-seven miles 

 per hour, but we have not traced a sufficient number to deter- 

 mine an average rate. 



As to the velocity of the wind along the line of damage in 

 these storms, we have no actual anemometer results, so far we 

 have not had one which passed over one of the anemometers, 

 but judging from the damage done to large and solid trees, 

 two and even three feet in diamettr, it cannot I think be 

 less than one hundred and forty or one hundred and fifty miles 

 per hour. 



We may now turn to the storms in the Narrabri district. The 

 storm reached Narrabri at 6. 15 p.m., and the postmaster reports 

 that the storm which approached Narrabri from north-west was 

 accompained by thunder and lightning, but no hail. The wind, 

 however, seems to have been of hurricane violence, trees two feet 

 in diameter were torn up by the roots, limbs twelve inches through 

 were snapped off short, a brick factory completely ruined,, 

 roofs, sign-boards, and everything that the wind could move 

 went flying ; in the language of the local newspaper, "sub- 

 stantial brick buildings came tumbiino: in all directions, the 



Photograph of iron perforated ^ 



air was full of iron tubs, galvanised iron, and tins of every 

 description." 



In the district south of Narrabri the storm was even more 

 severe. At Tulcumbah Station, fifty-seven miles south-east from 

 Narrabri, at 8 p.m. on October 13, a violent thunder and hail 

 storm broke over the homestead. It lasted half an hour, and 

 Mr. A. D, Griffiths, my informant and manager of the stationi, 

 says, " I measured some of the hailstones, six and a half inches 

 in circumference ; this was fifteen or twenty minutes after the 

 storm, and I think I did not get the largest. Next morning I 

 found that nineteen sheep had been killed by the hail, also birds, 

 kangaroo-rats, and other animals were found lying dead in all 

 directions. All the windows exposed to the storm were broken^ 

 and the galvanised iron roofing is dented from end to end> and 

 many sheets cut through : in several cases the hailstones went 

 through the iron ; in one sheet I found thirty holes, and in another 

 more than sixty. The bark of the trees in the storm track was all- 

 battered by the hail, and the fences and buildings bore traces o£ 

 the impact of these great lumps of ice. The stones were gener- 

 ally triangular or conoidal in form, many having an uneven sur- 

 face, which looked as if it had been formed from frozen drops of 

 water collected into masses ; others had an opaque snow-like 

 centre, perhaps the majority were like this, the remainder being 

 like clear ice. It was only the larger stones that were irregular 

 as described, the smaller ones were generally rounded," 



At Avondale, thirty miles north of Narrabri, my informant > 



