NOVEMBEK 23. 1899] 



NA TURE 



91 



designed and made of special material. The use of nickel steel 

 has enabled us to make the long cranks of. ample strength, 

 although they weigh very little more than short ones. The 

 strains introduced into the frame are mainly those due to chain 

 jiressure, and are not influenced by crank length but entirely by 

 the speed of the chain. The speed of the chain can be increased 

 by enlarging both the sprocket and back pinion wheels. Sum- 

 marising our results it appears — 



(1) That when we talk of designing the cycle to suit any 

 individual rider, so as to develop his powers as a motor to the 

 greatest extent, we have first to consider how we can best 

 economise his nerve waste by enabling him to reduce the number 

 of revolutions and increase the stroke through which his legs 

 can travel. Our experiments have shown us that these conditions 

 are best fulfilled in the great m.ajority of cases by giving to the 

 rider a length of crank equal to half the length of his thigh bone. 



(2) That the value of M the multiple, in other words the gear, 

 is then to be determined by the maximum strains which his 

 muscles will stand, and we believe in most cases this corre- 

 sponds to a pedal pressure F not exceeding loo lbs. for weak 

 individuals up to 140 lbs. for strong ones. 



(3) That the crank length determines the shape of the frame 

 and the length of the wheel base, and that the extra long wheel 

 base necessitated by the long cranks renders the cycle pleasanter 

 to ride and does not materially increase its weight. 



(4) That considering how important it is to reduce the 

 number of crank revolutions in order to economise nerve waste, 

 the cultivation of the pull stroke enables a greater average F 

 to be obtained without straining the muscles beyond their elastic 

 limit, and, consequently, allows of a higher multiple M and a 

 correspondingly reduced number of revolutions. Out of a 

 number of carefully made test runs we have selected the follow- 

 ing as representative of the increased efficiency which we have 

 obtained from the use of the lengthened cranks. The elder of 

 us, aged 54, height 5 feet 10 inches, thigh bone 18-inch shank, 

 from knee to ball of foot 21 inches, made a trial in the summer 

 of 1896 with a cycle having 6i-inch cranks, geared to 99I. 

 The total weight of rider and cycle was then 195 lbs., and the 

 surface exposed to the air, including cycle, was 5^ square feet. 

 The maximum distance that could be travelled on a good road 

 with an average wind was 78 miles in ten hours, including 

 rests, or in an actual riding time of 7| hours. The average 

 foot pounds per minute in this case was 2917. In September 

 1898 R. E. Crompton made a test on a cycle having cranks 

 9" I inches long, geared to 102. The weight of the cycle and 

 rider was, as in the former trial, made up to 195 lbs. The test 

 run was from Kensington Court, London, to Romseyin the New 

 Forest and back ; total distance 156 miles, total time 13 hours 

 28 minutes, riding time xo hours 54 minutes. The bodily 

 fatigue on this day was no greater than on the 78-mile run in 

 1896. In this ride the average foot pounds per minute through- 

 out the day was 6650, so that whereas with the old system of 

 short cranks in 1896, R. E. Crompton was able to maintain P 

 at 2917 for 7:1 hours, with the new system in 1898 he was able 

 to maintain 6650 for 10 hours 54 minutes ; in other words, from 

 a given amount of food or, what is the same thing, a given 

 amount of bodily fatigue, R. E. Crompton was in 1898, on the 

 long-crank machine, able to do three times as much work as he 

 did on the short-crank machine in 1896. Many other similar 

 runs have been made,' and other long-crank riders can produce 

 equally satisfactory results. 



The theory we have formed as to the nature of bodily fatigue 

 induced by cycle riding, in which we have endeavoured to show 

 the extreme importance of the part played by the brain and 

 nerve systems, and that probably the major portion of the 

 energy of the human body considered as a motor passes through 

 the brain and nerve tissues to energise the muscles, is a matter 

 which merits the careful attention of physiologists. Writers on 

 this subject have hitherto considered the human or animal motor 

 as a heat engine, all the useful energy being obtained by cor- 

 responding chemical work done on the muscles. We believe 

 that the greater part of the energy-yielding processes goes on 

 within the brain itself or in the nervous system directly con- 

 nected with the brain. Many facts observed by cyclists and 

 other athletes when carrying out feats of endurance show that 

 brain and nerve nourishment is to be aimed at rather than the 

 repair of muscle waste, and that certain foods and drinks have 

 to be avoided on account of their action in producing temporary 

 slackness ; in fact, on account of their preventing the brain 

 from effectively energising the muscles. 



NO. 1569, VOL. 61] 



JSiOlE ON THE DISTANCES TO WHICH 



EXPLOSIONS ARE FELT AND HEARD. 



CT. HELENS being situated in a thickly populated district, • 



the disaster at Messrs. Kurtz's works (belonging to the 

 United Alkali Company) seemed to offer a good opportunity 

 for determining how far a great explosion may be felt and 

 heard. Isolated observations, as will be seen below, have beei> 

 made on other occasions ; but, to feel confidence in the' results, 

 we require a fairly continuous series of records extending from 

 near the centre of disturbance to the boundary of the affected 

 area. I therefore wrote letters to all the more important news- 

 papers in the south of Lancashire and north of Cheshire, in re- 

 quest of observations either of the sound or of the movement of 

 windows by the air- waves. In reply to them, I received more 

 than fifty accounts, which, in addition to several which appeared 

 in the local press, gave a total of 61 records from 47 different 

 places. 



The immediate cause of the explosion was the firing of one of 

 the vessels used in crystallising the chlorate of potash, the 

 vessels being made of wood lined with lead. It is computed 

 that eighty tons of chlorate exploded. The whole of Messrs. 

 Kurtz's buildings were razed to the ground, and nine out of ten 

 great vitriol chambers on the other side of an adjoining road were 

 destroyed. Within a few hundred yards of the chemical works 

 there are many streets of workmen's cottages ; the doors, 

 windows, chimney-stacks of whole rows were dismantled, and, 

 in some cases, the roofs fell in. Within a radius of a mile or 

 so, hardly a window seems to have escaped ; ^ but according 



to one of my correspondents, who was in the north-west of the 

 town, the damage to windows around him was comparatively 

 slight. 



On the accompanying map are shown all the places from 

 which records of the explosion were obtained. \ small square 

 denotes a place where the air-wave was strong enough to make 

 windows and doors rattle ; if the square is filled in, the sound 

 was also heard. Places where the observation of the sound 

 only is recorded are represented by a circle if the observer was 

 out of doors at the time, and by a triangle if he was inside, or 

 probably inside, a house. A perceptible tremor of the ground, 

 strong enough to be mistaken for an earthquake, was felt at 

 some distance from St. Helens, but how far cannot be definitely 

 ascertained. 



It will be seen that the area over which the sound was beard 

 is practically the same as that in which the air-wave was strcmg 

 enough to make windows rattle. The bounding curve is ellip- 

 tical in form, 39^ miles in length from east to west, 27^ miles in 

 breadth, and includes an area of about 850 square miles. St. 

 Helens lies close to the longer axis of the curve and nine miles 

 to the west of the centre. Towards the east, the sound was 

 heard at Alderiey Edge (24^ miles from St. Helens) and at 

 Oldham (27 miles). Windows were observed to rattle at 

 Alderiey Edge and also at Marple (28 miles). To the west of 

 St. Helens the sound was heard at Liverpool ( 10 miles) and 

 Aughton (10 miles). I have tried in vain to ascertain the direc- 

 tion of the wind at the time of the explosion at different places 



1 The above particulars are obtained from the account giv-en in the 

 Manchester Guardian for May 13. 



