424 



REPORT — 1897. 



Comparing the three different methods of experiment, which all lead 

 to a similar result, it may be regarded as highly probable that the old' 

 view of an infinite rate of condensation requires revision, and that the 

 value of the rate of condensation of steam on a metal surface, as determined 

 by the author's previous experiments, is at least a first approximation to 

 the truth. The question at issue is one of fundamental importance in the 

 theory of the steam-engine, and the authors have shown in the Paper 

 already quoted that, if the law of condensation there proposed be admitted, 

 a number of interesting practical deductions can be made, and problems 

 may be solved which have not hitherto been regarded as amenable to other 

 than empirical treatment. 



Calibration of Instruments used in Engineering Laboratories. — 

 Apimulix to Report of the Committee, consisting of Professor A. B.. 

 W. Kennedy, F.E..8. (Chairman), Professor J. A. Ewing, F.R.S.,. 

 Professor D. S. Capper, Professor T. H. Beare, and Professor 

 AV. C. Unwin, F.R.S. (Secretary). 



The Committee obtained measurements of the elongations under tension 

 of a set of test bars made by different instruments and observers. A 

 comparison of the results was given in the Report for 1896, pp. 538-548. 



The Committee applied to Professor A. Martens, of the Technische 

 Hochschule, Charlottenburg, to make some similar measurements with 

 the instruments at Berlin, for comparison with the measurements made 

 in this country. Professor Martens very kindly consented to make these' 

 measurements, but his report was not received till February this year. 



The measurements at Berlin appear to have been made with the 

 greatest care, and with three different testing machines. The variation 

 in the extensions with different loads is less than that in most of the 

 measurements made in this country. 



The following is a general comparison of the average result obtained 

 at Berlin, with the average of all the results by different observers in this, 

 counti-y for corresponding bars : — 



Coefficient of Elasticity. {Tons j^er square inch.) 



The tables of details are appended : — 



Results of Tensile Tests made with Rod E. 



Diameter 

 Section 

 Measured Length 



Elongation-measurer 

 Machine . 

 Temperature of room 



<Zrz31'8 millimetres. 



F = 794-2 square millimetres^ 



L — 200 millimetres. 



Martens' Mirror Apparatus. 



Werder's System. 



^ = 16° to 17° Centigrade. 



