August 5, 1897] 



NATURE 



331 



which I hope mineralogists will forgive me. A very fine slab of 

 the meteorite, weighing about seven pounds, which has escaped 

 the solvent, is on the table before you. 



Here, then, we have absolute proof of the truth of the 

 meteoric theory. Under atmospheric influences the iron would 

 rapidly oxidise and rust away, colouring the adjacent soil with 

 red oxide of iron. The meteoric diamonds would be unaffected, 

 and would be left on the surface of the soil to be found by ex- 

 plorers when oxidation had removed the last proof of their 

 celestial origin. That there are still lumps of iron left at Arizona 

 is merely due to the extreme dryness of the climate and the com- 

 paratively short time that the iron has been on our planet. We 

 are here witnesses to the course of an event which may have 

 happened in geologic times anywhere on the earth's surface. 



Although in Arizona diamonds have fallen from above, con- 

 founding all our usual notions, this descent of precious stones 

 seems what is called a freak of nature rather than a normal 

 occurrence. To the modern student of science there is no great 

 difference between the composition of our earth and that of 

 extra-terrestrial masses. The mineral peridot is a constant 

 extra-terrestrial visitor, present in most meteorites. And yet no 

 one doubts that peridot is also a true constituent of rocks formed 

 on this earth. The spectroscope reveals that the elementary 

 composition of the stars and the earth are pretty much the same ; 

 so does the examination of meteorites. Indeed, not only are 

 the self-same elements present in meteorites, but they are com- 

 bined in the same way to form the same minerals as in the crust 

 of the earth. 



This identity between terrestrial and extra-terrestrial rocks 

 recalls the masses of nickeliferous iron of Ovifak. Accompanied 

 with graphite, they form part of the colossal eruptions which 

 have covered a portion of Greenland. They are so like 

 meteorites that at first they were considered to be meteorites till 

 their terrestrial origin was proved. They contain as much as 

 I •! per cent, of free carbon. 



It is certain from observations I made at Kimberley, corro- 

 borated by the experience gained in the laboratory, that iron at 

 a high temperature and under great pressure will act as the 

 long-sought solvent for carbon, and will allow it to crystallise 

 out in the form of diamond — conditions existent at great depths 

 below the surface of the earth. But it is also certain, from the 

 evidence afforded by the Arizona and other meteorites, that 

 similar conditions have likewise existed among bodies in space, 

 and that a meteorite, freighted with its rich contents, on more 

 than one occasion has fallen as a star from the sky. In short, 

 in a physical sense, heaven is but another name for earth, or 

 earth for heaven. 



THE INSTITUTION OF MECHANICAL 

 ENGINEERS. 

 "T^HE Institution of Mechanical Engineers was founded in 

 -•■ 1847, and the present year is therefore its jubilee. As it 

 came into existence as a Birmingham Society, and for the first 

 thirty years of its career had its offices in that city, the removal 

 to London being made in 1877, it was appropriate the jubilee 

 meeting should be held there. 



The meeting commenced on Tuesday of last week, July 27, 

 and was brought to a close on the following Friday. There 

 were two sittings for the reading and discussion of papers held 

 on the Tuesday and Wednesday mornings, the President, Mr. 

 Mr. E. Windsor Richards, occupying the chair. There were 

 five papers on the agenda, but time was only found for the 

 reading of the following three : — 



"Some points in cycle construction," by F. J. Osmond, of 

 Birmingham. 



" The City of Birmingham Corporation Waterworks," by 

 Honry Davey, of London. 



" High-speed self-lubricating engines," oy Mr. Alfred Morcom, 

 of Birmingham. 



The President also read an address, in which he gave par- 

 ticulars of the founding and early history of the Institution, 

 together with short biographical notices of its past-presidents, 

 from George Stephenson, who was the first, down to the present 

 day. 



Mr. Osmond, in his paper, discussed a few of the points to be 

 observed in designing a successful bicycle. The principal 

 causes of inefficiency, he said, were want of rigidity and undue 



friction. Of these two he considered the lormer the most 

 important, and it is in this particular that cycles differ far more 

 than in friction. The cause of loss is twofold. Firstly, the 

 work done in springing the frame out of shape at each stroke of 

 the foot is not spent in driving at the end of the down-stroke, 

 but only in lifting the foot at the beginning of the up-stroke. 

 Secondly, the springing of the frame causes a general condition 

 of instability, due partly to the alteration of the balance through 

 lateral movement of the pedals, and partly to the wheels being 

 forced out of line, thereby causing the machine to swerve from 

 side to side instead of running a true course. Purchasers of 

 bicycles would do well to remember these facts. The rage for 

 lightness is so great, that the makers, who have to follow the 

 fashion, often cut material down to a point where there is only 

 just enough metal to support the rider's weight under the varying 

 conditions of running, the factor of safety being perilously small. 

 As to rigidity, that is often abandoned altogether, or at 

 any rate is only considered so far as it does not add 

 to weight. Considering that the average purchaser only 

 tests the machine by spinning the wheels and pedals 

 to see if they run easily, one cannot wonder at this abandon- 

 ment of a vital principle by the maker ; but perhaps after 

 the warning of Mr. Osmond, himself a noted manufacturer of 

 cycles, sounder principles may prevail. In well-constructed 

 machines friction is mainly due to the chain, and it is said that 

 no more than I per cent, of the total power exerted by the rider 

 has been lost. Even allowing a much higher factor than this, 

 and doubtless it is too small, it will be seen to what perfection 

 ball bearings have enabled the cycle maker to produce his 

 machines. Mr. Osmond thinks that a mechanical efficiency of 

 95 per cent, would be nearer the truth, and this would be some- 

 what lower than the best record with which we are acquainted 

 for the steam engine. The factor of safety for the bicycle 

 frame is about i^, and if this is to be taken as including the 

 ordinary conditions of riding, Mr. Osmond considers it true ; 

 but he states that a well, built frame will carry at least ten times 

 its natural load without injury. The difference is due to the 

 fact that the front part of the frame is exposed to shocks which 

 must cause bending stresses near the head. If the two front 

 tubes are arranged so that their axes intersect vertically above 

 the axle of the front wheel, the stresses are only pure tension and 

 compression so long as the force acting through the front axle 

 is purely vertical. Such conditions are naturally not present 

 when the wheel meets an obstacle, and bending stresses 

 are therefore introduced. Other details of construction 

 were discussed in the paper, and were illustrated by numerous 

 wall diagrams. The discussion on this paper was confined 

 to the suggestion by one speaker, Mr. Sharp, of Birmingham, 

 that the weakening effect of brazing together the members of 

 frames might be overcome by making a mechanical joint 

 in which a hollow plug of suitable formation should be in- 

 serted in the ends of two tubes to be connected, the plug being 

 corrugated on the outside, the idea being that the tube ends of 

 the tubes containing the plug should be pressed into the corru- 

 gations. The joint would seem difficult to make, and one would 

 fear that even if tightly made in the first instance it would be 

 likely to work loose in time ; but we are assured by the inventor 

 that the device has given most promising results in actual prac- 

 tice. If these promises can be confirmed, the invention is of 

 considerable value, as the brazing of steel undoubtedly causes 

 deterioration of the metal. 



Mr. Davey's paper gave an historical and general account ot 

 the Birmingham water works, together with cost of pumping, 

 &o. This contribution led to practically no discussion. 



Mr. Alfred Morcom's paper was far the most important of the 

 three, and indeed was an excellent example of what a contribu- 

 tion to the proceedings of this Institution should be. The author 

 is managing director of the firm of G. E. Belbis and Company, 

 who have for some time past devoted their resources largely to 

 the construction of what are generally known as high-speed 

 engines, for which of late there has been a large demand owing 

 to the spread of electric generation for lighting and power pur- 

 poses. The engines of this firm differ from those largely manu- 

 factured for like purposes in the fact that the cylinders are 

 double-acting, steam being taken on both sides of the piston. 

 For very high speeds of rotation it has been often said to be 

 necessary, in order to give smooth running, that there should be 

 no reversal of stress on the working parts ; steam, therefore, 

 has generally been admitted only above the piston, so that the 



NO. 1449, VOL. 56] 



