Dec. lo, 1S85J 



NATURE 



135 



hence the driving wheels, which nevertheless can move 

 independently. Other gears were spoken of, and a figure 

 of the Sparkbrook gear given. 



Each kind of driving has its advantages. When run- 

 ning straight the clutch system drives each wheel, and 

 when one wheel meets with more resistance than the 

 other, as much extra force as is necessary is supplied to 

 it, so that obstacles are surmounted with less chance of 

 swerving. In going round a corner only the inner wheel 

 is driven. 



With balance-gear the same force is applied to each 

 wheel, whether the path is straight or curved. 



A rear steering tricycle driven by clutch action, a rear 

 steerer driven by differential gear, and a front steerer 

 driven by differential gear were exhibited. 



Huinber T^zV^dYf.— Among tricycles driven by differen- 

 tial gear, the Humber is quite peculiar. The rider sits 

 astride a back bone carrying a trailing wheel, and steers 

 by turning the axle of the two driving wheels by means of 

 a handle bar. The differential gear is essential to a 

 machine of this type, as it does not interfere with the 

 steering, while it is at all times perfectly double 

 driving. 



A curious machine — a modification of the Humber — 

 was shown, in which all three wheels take part in the 

 steering, but of entirely novel and elegant design. 



As with bicycles, so w^ith tricycles, the power may be 

 applied in one of two ways : either by rotary action or by 

 lever action. For changing the power, levers are more 

 convenient, but they do not compare with rotary action 

 in point of speed. 



OmiiicyLh\—On& of the most successful lever machines 

 is the omnicycle, a machine in which the pedals are con- 

 nected with the circumference of a segment by means of 

 a leather strap. When one pedal descends it causes the 

 segment on the other side to return and raise the pedal 

 on that side. The segments can be expanded to various 

 extents, so that the power is applied with various degrees 

 of leverage according to the work to be done. 



Dinci-Action Tricycle. — The simplest rotary tricycle 

 has no chain or connecting mechanism ; the pedals are 

 on the main axle, which is cranked. This gives rise to 

 the insuperable objection of instability as the rider is 

 necessarily perched up high. By the use of hanging 

 pedals a few inches are gained. 



Transmission of Driving-power. — Reverting to the 

 ordinary type of tricycle in which the power is applied to 

 a crank axle and transmitted thence to the main axle, 

 there are three plans commonly in use — (i) by chains or 

 bands : (2) by gear wheels ; (3) by cranks and coupling- 

 rods. 



Driving-Cltains, These are the most popular means 

 of transmitting power, as they offer the greatest facilities 

 for gearing up or down. The Morgan and the Abingdon 

 chain were figured and described. 



Driving- Bands. — Steel bands, plain or perforated, have 

 been used with some success. The Otto bicycle is the 

 only machine in which plain bands are used for driving. 

 The power spent in continuous flexure of the bands out- 

 weighs, in the author's opinion, any other advantages they 

 may possess. 



Gear- Wheels. — In this system an intermediate wheel 

 gears with those on each axle ; but as the wear cannot be 

 taken up without destroying the pitch, the plan is hardly 

 satisfactory. Jiollers are occasionally fitted over the teeth 

 of the intermediate wheel. 



Couptim^-Rods. — Coupling- rods are used on a few 

 machines ; with the exception that they will not permit 

 of gearing up or dow-n and that they cannot be used 

 with differential gear, they give very good results. 



Another method due to Mr. Boys, in which eccentrics 

 and steel bands are employed, was also referred to. 



{To be continued.) 



NOTES 



Dr. Asa Gray was presented, on November 18, being the 

 seventy-fifth anniversary of his birth, with a silver vase, by the 

 botanists of America. It is described by Science as being about 

 eleven inches high, and is appropriately decorated with those 

 plants which are distinctively American, and which are most 

 closely associated with Dr. Gray. The place of honour on one 

 side is held by Grayia polygaloidcs, and on the other by Shortia 

 galacifolia. Among others, Aster Bigelovii, Soliiiago serotina, 

 Liliiim Grayi, Centaurea americaita, Notholetia Grayi, and Rud- 

 beckia spiciosa, are prominent. The workmanship is described 

 as highly artistic, as well as remarkably accurate. The vase 

 stands on a low ebony pedestal, which is surrounded by a silver 

 hoop, bearing the inscription : — 



iSio — November Eighteenth — 1885 



ASA GRAY 



In token of the universal esteem 



of American botanists. 



The greetings by card and letter of the one hundred and eighty 



contributors were presented on a plain but elegant silver tray. 



They contained the warmest expressions of esteem and 



gratitude. 



As we intimated last week, the death took place in Paris, on 

 the 30th ult., of M. Bouley, President of the Academy of 

 Sciences, after a long and painful illness. Although, says the 

 Revue Scientifique, he did little original work in science, he 

 exercised a wide influence on its general progress as well as on 

 scientific education. He did much lo raise in public considera- 

 tion the art and science of veterinary surgery and medicine. 

 Latterly, he became the ardent apostle of the teachings and dis- 

 coveries of M. Pasteur, and to this work he devoted his lucid 

 and vigorous eloquence. His books on experimental disease 

 and on contagion are models of scientific style, as his lectures at 

 the Museum were models of instruction. 



The death is announced, at the age of eighty years, of Prof. 

 Giuseppe Ponzi, the Italian geologist. 



The fifth edition of the "Admiralty Manual of Scientific 

 Inquiry " is now being prepared for press, under the editorship 

 of Prof. Robert S. Ball, F.R.S., Royal Astronomer of Ireland 

 The following is a list of the articles, with the names of the 

 authors or revisers : — Astronomy, by Sir G. B. Airy, K.C.B. , 

 F.R.S. ; Hydrography, by Capt. W. J. L. Wharton, RJM., 

 Hydrographer of the Admiralty ; Tides, bj- Prof. G. H. Darwin, 

 F.R.S. , ; Terrestrial Magnetism, by Prof G. F. Fitzgerald, 

 F.R.S. ; Meteorology, by Robert H. Scott, F.R.S. ; Geo- 

 graphy, by Sir J. H. Lefroy, F.R.S. ; Statistics, by Prof. C. 

 F. Bastable, M.A. ; Medical Statistics, by W. Aitken, M.D. ; 

 Ethnology, by E. B. Tylor, F.R.S. ; Geology, by Prof. Archi- 

 bald Geikie, F.R.S. ; Mineralogy, by Prof W. J. SoUas, 

 D. Sc. ; Earthquakes, by Thomas Gray; Zoology, by Prof H. 

 N. Moseley, F.R.S. ; Botany, by Sir J. D. Hooker, K.C.S.I., 

 F.R.S. 



Now that M. de Lacase-Duthiers has completed his arrange- 

 ments for the marine laboratories at Banyuls and Roscoff, his 

 friends and admirers have deemed the moment a suitable one 

 for manifesting their sense of the value of his services to the 

 study of zoology in France, and to zoologists all over the world, 

 and it is hoped that all those who are connected, either by their 

 studies or their sympathies, with the zoological school founded 

 and directed by him, will join in the work. The proposal is to 

 have his portrait etched by one of the best French artists, and 

 to give a copy to each subscriber of ten francs or more. The 

 number of copies will be strictly limited to the number of sub- 

 scribers. The Universities or schools of Athens, Paris, Caen, 

 Geneva, Riege, Cairo, Edinburgh, Clermont, Besan9on, Lyons, 



