REMARKS ON DRAINING. 



119 



the cock was withdrawn from the box, and more free egress of 

 water being thus afforded, at 35 minutes the flow was no longer 

 continuous, and the thermometer b indicated 48°. The mass was 

 drained and permeable to a fresh supply of water. 



Accordingly another gallon of boiling water was poured over 

 it, and in 



3 minutes the thermometer a rose to 77° 

 5 „ „ fell to 76J 



15 ,, ,, 71 



20 „ remained at 70 J 



lh. 50 „ „ „ 70^ 



In these two experiments the thermometer at the bottom of 

 the box suddenly rose a few degrees immediately after the hot 

 water was added ; and hence it might be inferred that heat was 

 carried downwards by the water. But in reality the rise was 

 owing to the action of the hot water on the thermometer, and not 

 to its action upon the cold water. To prove this the perpen- 

 dicular thermometers were removed : the box was filled with 

 peat and water to within three inches of the top ; a horizontal 

 thermometer (af) having been previously secured through a 

 hole made in the side of the box by means of a tight-fitting cork, 

 in which the naked stem of the thermometer was grooved. A 

 gallon of boiling water was then added. The thermometer, a 

 very delicate one, made by Newman, was not in the least affected 

 by the boiling water in the top of the box. 



Experiment No. 3. — Silver-sand was put into the bottom of 

 the box so as to be a little above the bulb of the thermometer fa, 

 with the view of protecting it when introduced ; the box was 

 then filled with yellow loam as far as c. The loam was then 

 saturated with water from the rose of a watering-pot. Numerous 

 air-bubbles rose when saturation had been nearly effected, the 

 whole surface of the soil being just covered with water : the 

 latter subsided as the air found its way out. The thermometer 

 f a was then introduced, and it soon acquired the temperature of 

 the mass, 45°. A handful of straw was squeezed together and 

 laid on the top of the soil to break the force of the hot water, a 

 gallon of which when boiling was poured on. The hot water 

 cooled by evaporation, but produced not the least effect on the 

 delicate thermometer f a near the bottom of the box. Another 

 gallon of boiling water was added when the first had cooled down 

 to 100° ; but the thermometer f a still indicated 4.5°. Any per- 

 son can easily make similar experiments. It is best to introduce 

 the thermometer through the side of the box, as at f ; for if 

 plunged from the top the boiling water surrounding a portion of 



