590 



NATURE 



[February 29, 1911- 



are thin and therefore light, and yet rigid and strong. 

 One of these is a pretty little pair for ladies' use, 

 weighing only six ounces, in a dainty case (fitted with 

 a mirror and a small pocket), which yet has a mag- 

 nification of four diameters, and an angular field of 

 view of 11°, equivalent to a field 193 yards wide at 

 1000 yards. These are greater than would be obtained 

 by an old pattern opera-glass of large size, and are 

 very much greater than the magnification and field of 

 the small ones usually carried by ladies, for which 

 the former is often only two or three diatneters. 

 Even with the case the weight is but thirteen ounces. 



A corresponding glass of the same power and aper- 

 tuii i^ .ilso made for field use. In addition to ilu- 

 itnii.il lu( ussing screw one of the eye-Ienscs has an 

 independent focussing adjustment for correct inj^ anv 

 difTerence in refraction between the eyes nt tlie 

 observer. 



Another glass very suitable for all-round use, 

 magnifying six diameters and weighing a pound, 

 gives good definition over a field of 8°. To see the 

 whole field at once, however, the eye has to be put 

 uncomfortably close to the eye-piece ; in ordinary use 

 the field may be taken to be about six or seven 

 degrees. 



The brightness of the image depends upon the 

 aperture of the objective (of course, also on the absorp- 

 tions of the glass of the prisms and lenses, and the 

 internal reflections). Leitz makes two models mag- 

 nifying eight diameters, the one of which has an 

 objective one inch in diameter ; the other has a 

 diameter of one and a quarter inches ; with a centre 

 focussing screw, they weigh eighteen and twenty- 

 three ounces respectively without the case. The 

 larger one gives a much brighter Image, but this, as 

 stated above, is unnecessary in ordinary circum- 

 stances. It is intended to be used at dusk; it is an 

 ideal glass for a naturalist, for instance, for watching 

 wild life in a dark wood. It is dust- and damp-proof. 



High powers require a steady hand to get their full 

 value ; the elght-dlameter can be used comfortably by 

 most people, especially if the arm or elbow can be 

 supported. But powers above this magnify the 

 tremors of the hand so much that they are only of use 

 for special work. Leitz makes ten-diameter and 

 twelve-diameter models. These have large objec- 

 tives and remarkably high luminosity of Image ; for 

 their power their angular field is also high. 



PROF. OSBORNE REYNOLDS, F.R.S. 



T N Prof. Osborne Reynolds, whose death took place 

 •• on February 21 at Watchet, Somersetshire, Great 

 Britain has lost Its most distinguished scientific 

 engineer. He was born at Belfast on 1842, but spent 

 his childhood in Suffolk, where his ancestors had, for 

 generations, been rectors at Debach and Boulge. 

 Having received his school education at Debenham, 

 he entered Queen's College, Cambridge, and after a 

 brilliant academic career, became a fellow of his 

 college in 1867. 



The chair of civil and mechanical engineering at the 

 Owens College was founded a year later on the 

 initiative of the leading engineers of the Manchester 

 district, and endowed by them. A committee, on 

 which were such men as William Falrbairn and 

 Joseph Whitworth, selected Revnolds as the first occu- 

 pant of the professorship. The foundation of the 

 Whitworth scholarships, ten of which were reserved 

 for Manchester students. Immediately followed, and 

 gready assisted the early work of ' the School of 

 Engineering. It is of Interest to note the names of 

 Tohn Hopklnson and J. J. Thomson among the 



NO. 2209, VOL. 88] 



students who received their instruction from Osborne- 

 Reynolds. Practical instruction in engineering was 

 unknown, when engineering was first included among 

 the subjects taught at university colleges, and it was 

 not until Reynolds had held his chair for nearly twenty 

 years, that funds became available for the building 

 of a laboratory. The Whitworth Laboratories at Man- 

 chester and -Sir Alexander Kennedy's laboratory at 

 University College were the first of their kind, and 

 served as models for other similar institutions 

 throughout the country. 



During a period of over thirty years Reynolds was 

 actively engaged in scientific work, Including in his 

 wide field of investigation many important problems 

 of engineering and physics. Well in advance of his 

 time, in many cases years elapsed before the practical 

 bearing of his researches was fully appreciated ; even 

 now the sphere of his influence on engineering pro- 

 gress is still widening. 



In 1874 Reynolds published his first papers on 

 ■' Heat Transmission," in which he showed that in 

 most practical cases the motion of the gas, and not 

 its conductivity, was the controlling factor. Nearly 

 thirty years later, the attention of engineers was 

 directed to this work by Perry, and the principle 

 applied to boiler construction by Nicholson and others. 



Experimenting with steam, Reynolds found that in 

 the absence of any admixture of air, the rate of con- 

 densation was practically unlimited, and he studied 

 the efTect of air on the cooling surface required, and 

 the efficiency of the condenser. Very high vacua are 

 not required for the ordinary reciprocating engine, 

 and it was only in recent times, and owing to the 

 Introduction of the steam turbine, that the theorv of 

 condensers became of supreme importance, and Rey- 

 nolds 's work found its application. 



During the six years ending 1880 numerous papers 

 were read by Reynolds at the Institute of Naval Archi- 

 tects, the problems of the steering of ships and the 

 efliciency of the propeller itself being the chief subjects 

 under discussion. The Importance of the phenomenon 

 of cavitation, which had been studied by Reynolds in 

 some detail twenty years before, was not generallv 

 recognised until, in 1897, the steam turbine was first 

 applied to marine propulsion. 



In 1SS7 a paper on the use of models for deter- 

 mining the regime of rivers and estuaries was read 

 by Reynolds at the British .Vssociation, and led to the 

 appointment of a committee to pursue the subject. 

 On behalf of this committee Reynolds carried out a 

 series of experiments which were published in three 

 successive reports. The work attracted considerable 

 attention, and a special commission was sent from 

 Paris to obtain his advice with regard to the drainage 

 works then in course of construction in the Seine 

 estuary. 



A large number of Reynolds's papers deal with 

 problems in hydraulics. Having devised an in- 

 genious method of delineating the stream lines by the 

 introduction of colouring matter, he proved that there 

 is a critical velocity at which the flow of water in a 

 pipe becomes turbulent, and measured its magnitude. 

 By an application of the principles thereby involved, 

 he was enabled to design the first workable multi- 

 stage turbine pump, of which he must be regarded as 

 the originator ; and in the further pursuance of related 

 questions, he was led to the more theoretical and 

 mathematical discussion of vortex motion and lubrica- 

 tion. 



In 1S89 Reynolds published a set of trials on a 

 loo-h.p. steam engine, which he had specially de- 

 signed to meet the requirements of his experimental 

 work. These trials are repeatedly quoted in technical 

 publications as standard examples of engine tests. 



