J. 0. Thompson — Law of Elastic Lengthening. 41 

 Table of 10 Series of Measurements. 



Kg. 























Mean mm. 



0*2 



7-10 



•13 



•12 



•11 



•105 



•12 



•11 



•11 



•12 



•09 



7-111 



0-4 



14-25 



•265 



•26 



•28 



•285 



•27 



•265 



•27 



•28 



•27 



14-269 



0-6 



21-47 



•50 



•50 



•50 



•485 



•495 



•49 



■475 



•49 



•49 



21-489 



0-8 



28-76 



•775 



•78 



•77 



•75 



•785 



•77 



•77 



•79 



•77 



28-772 



1-0 



36-11 



•125 



•14' 



•145 



■115 



•13 



•13 



•11 



•12 



•12 



36-124 



1*2 



4353 



•57 



•56 



•55 



•555 



* 



•57 



•55 



•545 



•56 



43-554 



1*4 



51-05 



•07 



•065 



•07 



•065 



•06 



•065 



•09 



•055 



•08 



51-067 



1-6 



58-66 



•71 



•685 



•71 



•66 



•69 



•675 



•68 



•69 



•675 



58-683 



1-8 



66-33 



•355 



•335 



•36 



•32 



•35 



•31 



•32 



•34 



•32 



66-334 



Ten additional series of measurements were made. The 

 mean values derived from the 20 series are given in the follow- 

 ing table under x observed. 



p- 



x observed. 



x calculated. 



Observed-calc 



0-2 k£. 



7-111 



•110 



+0-001 



0-4 



14-272 



•271 



+ 1 



0-6 



2T488 



•488 



± o 



0-8 



28-770 



•770 



d= o 



1-0 



36-119 



•122 



— 3 



1-2 



43-554 



•554 



dz 



1-4 



51-076 



•071 



+ -5 



1-6 



58-679 



•681 



— 2 



1-8 



66-341 











Mean temperature, 9°. 



Cross-section of wire, 0*0627 mm. 2 



Length of wire, 22700 mm. 



Specific gravity of wire, 8-42 



Initial load, 0*665 kg. 



p = added weight, and x = lengthening. 



Expressing the result of the measurements by an equation 

 of the form 



x = ap -f- bp*-{- cp* 

 I obtained the equation 



x— 35*4385 p -f 0*5353 p* + 0*1487 p 3 



The calculation of the most probable values of the constants 

 a, b and c, was effected in this case, as in all the other cases, 

 by means of the method of least squares. The mean error of 

 the individual measurements calculated from the 10 lengthen- 

 ings produced by a weight of 1*4 kg. and given in the table on 

 p. 41, is 0*011 mm. and the probable error of the mean result 

 is 0*0024 mm. Two minutes after the weighting and release 

 of the wire the mean lowering of the zero-point was 0*009 mm. 



*Nb measurement was made. If I had waited for the mark to come to rest the 

 after-effect would have been noticeable. 



