Sept. 12, 1884.] 



KNOWLEDGE ♦ 



217 



sea. The forest itself, properly so called, was for the most 

 part thus destroyed. It was the decaying refuse of the 

 forest, intermixed with the lowlier growths, which formed 

 the coal-seam as it now exists. Amongst these were the 

 lower parts of the trunks of the ancient forest-trees. These 

 became converted, like the rest of the vegetable matter, 

 into coal. 



But it may be asked how those portions of the trunks 

 which still remain above the level of the vegetable 

 layer are to be accounted for. Are we to suppose that 

 they remained erect after the sea had made its way into 

 the domain of the ancient forest 1 Many geologists think 

 so ; and doubtless the stumps of stout trees might resist for 

 a long time the action of the sea waves. But there seems 

 good reason for believing that, when the submergence first 

 took place, these stumps stood but little above the upper 

 surface of the vegetable layer, or that in many instances 

 the trees were broken off even below that level. Then, as 

 the pressure of the superincumbent layer gradually in- 

 creased with the layer's increase of thickness, the vegetable 

 matter was pressed down below its former level, and the 

 stumps were left standing above the depressed surface of 

 the vegetable layer. This explains the conversion of the 

 bark of these stumps into coal, since there is every reason 

 to believe that stumps simply left imbedded in sandstone 

 would not change into pure coal. 



In passing, I may remark that in whatever way it 

 happened that the stumps of the ancient forest-trees re- 

 mained standing above the level of the vegetable mass 

 forming the coal-seam, a strange result has followed. The 

 upper part of the stem became filled, as I have said, with 

 sandstone, forming a cast of the interior of the ancient tree ; 

 the bark became coal ; and outside the bark is sandstone 

 again. Thus there is a mass of sandstone separated from 

 the surrounding sandstone by a tube of coal. This mass 

 is not cylindrical, being larger below than above ; so that 

 if in any way the mass ceases to be supported, it falls like 

 a bolt from a gun. But in working the coal-seam the 

 material which had supported the sandstone mass is neces- 

 sarily removed. Hence the miners look with dread on 

 these coal-pipes, as they are called, which each year cause 

 fatal accidents in the Newcastle and other coal-fields. As 

 Sir Charles Lyell well remarks : " It is strange to reflect 

 how many thousands of these trees fell originally in their 

 native forests in obedience to the law of gravity, and how 

 the few which continued to stand erect, obeying, after 

 myriads of ages, the same force, are cast down to immolate 

 their human victims." 



(To he continued.) 



NOVEL TRICYCLES. 



By John Browning. 



(Chairman of the London Tricycle Cluh.) 

 THE ElIPEEOK. 



HAVING obtained one of these very novel machines, I 

 took it to Reigate to give it a thorough trial. On 

 mounting the machine, for the first few minutes' riding my 

 course was somewhat erratic, showing that it requires a 

 little practice in steering. The difficulty was soon sur- 

 mounted, and I may say at once that the machine is 

 certainly easier to steer that the Humber, and that with 

 experience it is completely under control. 



The method of applying the brake by means of the left 

 foot is very peculiar, and at first a rider feels awkward in 

 using it, but this feeling soon wears oft'. When running 



down a long hill with varying grades it seems difficult to 

 vary the pressure of the brake with the foot ; yet there is 

 a simple method, as I discovered in my second ride, by 

 which this may be done with the greatest delicacy. 



Whenever the brake has to be applied continuously for 

 some time, the left foot should be put on the brake- 

 pedal just above the axle, and the right foot on the 

 opposite, or right-hand side of the axle, then a slight lifting 

 action of the rir/ht foot — that is, a slight decrease in the 

 pressure of the right foot — will cause an increase of pres- 

 sure on the left foot, and thus the brake can be applied as 

 geutly as any hand-lever brake, and the pressure regulated 

 with as much nicety. I agree with Mr. Bennett, who tells 

 me that he has ridden 1,500 miles on the Emperor, that it 

 is desirable that the power of the brake should be in- 

 creased for the steepest, that is, downright dangerous hills. 



The Emperor is a good hUl-climber. I have ridden the 

 Woodhatch-hill, out of Reigate on to Earlswood-common, 

 on a machine geared to 52 in., and that without practice 

 and without strain. Some skill is undoubtedly required to 

 ride the Emperor, but what it requires, more than skill, is 

 confidence. It looks and feels a risky thing to do, to put 

 your feet up on the axle when flying a hill, but it is 

 tolerably easy and safe to do it, unless the hUl is almost 

 unrideably steep. 



The machine is made with 42-in. side-wheels, geared to 

 52 in. The hind wheel, which is about 30 in. diameter, is 

 the driving-wheel, and is driven by means of a chain. The 

 machine is a front-steerer, both the front wheels moving with 

 the axle for steering. It is, of course, a single driver, but 

 I have not as yet found the driving-wheel slip, either on 

 mud or dust, even when climbing hills. Some contrivance 

 is required for tightening the chain when it becomes slack. 



The Emperor can be mounted or dismounted either from 

 the front or behind. 1 prefer to mount it behind from 

 the pedal, and dismount from the front over the axle. 



There is no fear of falling head first out of this machine 

 when descending a hill, as, if the feet are in their proper 

 place on the brake and axle, the rider has an open front 

 before him, and can always come down on his feet. 



If the Emperor were made about 5 lb. or 10 lb. 

 lighter — and this might easily be done — and a little more 

 brake power were given, the machine would, I think, take 

 a good position, and soon be a favourite. 



But as back-pedalling can only be performed with one foot, 

 the brake on this machine is all important, and unless the 

 brake-power on the hind driving-wheel can be increased — 

 which I venture to doubt — it will be necessary to apply 

 band-brakes to both the front wheels, which might be done 

 readily by means of a hand-lever ; and to this moat riders 

 would give the preference. 



The Emperor may be obtained of Mr. Brooke Hitching, 

 the tricycle agent of Ludgate-hill, E.G. 



THE COVENTRY CHAIR. 



A year or more ago I suggested in Knowledge that 

 Sociable tricycles might be employed at country railway- 

 stations to carry passengers and luggage. 



Messrs. Starley &. Sutton, the manufacturers of the 

 Meteor and the Rover, have brought out a modified tricycle 

 which they call the Coventry Chair. This is intended to 

 supersede the present Bath Chair, which is now generally 

 dragged along at a crawling pace of about two miles an 

 hour at the utmost. The Coventry Chair can be driven 

 easily at a pace of five or six miles an hour. The wheels 

 have india-rubber tyres, and the chair is mounted on 

 tricycle springs ; the motion is therefore easy and pleasant. 

 The engraving shows that the invalid sits on a light wicker 



