126 



Pte. J. A. Hughes on the 



These are also shown in curves (fig. [4), the loss of heat 

 having been plotted against the velocity. 



Fig. 4. 



1250 



Cylinders \ /l)iam-5-0~6 







/ 







< 

 1 









IOOO 





















Q. 











8 









750 



^» 





Otam. /•£ 



3 cms. 















I ; 

























Diam 81 en 



'5*^ 



25 O 







^^l/cm ■« 



lens 

 cms 





{/^ 



'~<~~ 



.Length 69 





£-- 



Vei 



:Uy iQ metres p 



-rsec. 



■i. 







/ 







' 





/ 



/f Diam IS -5 cms. 

 J. Length ZOcms* 



7 J 



! 





Veloctty 



These curves show that the heat-loss is a function of the 

 velocity which may approximately be represented by 



K=kv\ 



In order to find the index w, log H is plotted against 

 log V, and a straight line drawn through the points. The 

 inclination of this straight-line graph gives n. 



The values of n obtained for the various cylinders are 

 exhibited in Table III. 



Table III. 



n. 



Diameter. 



•55 



•43 cm. 



•6 



•81 „ 



•65 



1'93 „ 



•7 



5-06 „ 



*98, *6 at low velocities. 



15-5 „ 



The above table shows that n increases from *5 for 

 cylinders of very small diameter to 1 for cylinders of large 



