336 Mr. T. Tate's Experimental Researches on the 



stand closed for some hours, the air in it became fully saturated 

 with the vapour of the water at the given temperature. The 

 thermometer with its dry woollen cap was then placed in the 

 humid-air bottle, and the rates of augmentation of temperature, 

 &c, were duly observed. 



Table of results of Experiment. Heating effects of dry Woollen 

 Cloth placed in Air saturated with the vapour of Water. 





Rate of aug- 



Maximum 



Correspond- 







Temperature, 



mentation of 



augmentation 



ing tension of 



Value of v by 



Value of E by 



in degrees 



temperature 



of tempera- 



vapour at T 



formula 



formula 



Cent., 



per minute, 



ture, 



temperature, 



v — 4-3p. 



E = 5-15x l-0512 T - 



T. 



v. 



E. 



P- 







2 







•9 



o 



57 



•208 



°-89 







5-6 



7 



1-2 



73 



•295 



1-24 



7-27 



11-6 



1-8 



9-2 



•410 



1-76 



919 



15 



20 



10-8 



•497 



213 



10-89 



20 



3-0 



140 



•686 



2-95 



13-98 



Here the near coincidence of the results given in the second 

 and fifth columns shows that the rate of augmentation of tempe- 

 rature is proportional to the tension of the vapour at the given tem- 

 perature. Also, the near coincidence of the results given in the 

 third and sixth columns shows that, within this range of tempe- 

 rature, the maximum augmentation of temperature is in the geome- 

 trical ratio of the temperature. This remarkable result admits of 

 the following theoretical exposition. 



Assuming, in accordance with the principles derived from the 



foregoing experimental results, E= -^; then, within certain limits, 



«j 



p=p k T , where p = the tension of vapour at 0°, and £= 1*0686, 



the ratio of the successive values of the tension of vapour for 



increments of 1°; hence we find 'E=r.apJ—J =cel; whence, by 



eliminating the constants c and e } we find E = 5*15 x 1-05 12 T . 



3. The maximum augmentation of temperature was found to 

 be affected by the thickness of the material ; thus a single fold 

 of woollen cloth at the temperature of 11° gave an augmentation 

 of only 6°, whilst the double fold gave 9°; again, the single fold 

 at the temperature of 20° gave an augmentation of 9°, whilst the 

 double fold gave 14°. This double fold, for ordinary tempera- 

 tures, was found to give the maximum effect. Also a single 

 fold of calico at 14° gave an augmentation of 4°*6, whilst the 

 double fold gave 5°'8. 



4. As the ratio - is constant for all temperatures, a thermo- 



