Philosophical Transactions of the Royal Society of London Volume 166
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1877 edition. Excerpt: ...accurate measurements. 158. Having found such an antagonistic action of dark heat, I tried the action of ice. This, I have already shown (33, 88), is equivalent to warming the opposite side of the instrument. A piece of ice brought near the radiometer on one side cuts off the influx of heat to it from that side, and therefore allows an excess of heat to fall upon it from the opposite side. The same radiometer that I used in the experiments with boiling water (155) was mounted with a candle the same distance off as before, so that one revolution took place in one minute. A lump of ice was now brought within half an inch from the bulb on the opposite side to the candle. The revolutions got slower, each arm as it passed seeming drawn towards the ice, and having a difficulty in moving away from it. At last the movement stopped altogether, an arm pointing direct to the ice, and being apparently held there by a powerful attractive force. Bringing the candle nearer caused the arms to oscillate a little; and when it was almost close to the bulb the force of the light overcame the action of the ice, and the arms revolved again, but irregularly and with jerks, the disks moving quickly to the ice and leaving it with difficulty. In this action of ice no preference was noticed for either the black or white surface. 159. A very delicate radiometer, in 2-inch bulb (152), was placed in a light just sufficient to see it distinctly by, but not enough to cause it to move. I then came out of a warm room and stood near it. In a few seconds it began to move slowly round, but the motion was negative, i. e. the black disks advanced instead of retreated--the action of the radiation of low intensity from my body being apparently to repel the white surface more...
- 189 x 246 x 17mm | 576g
- 13 Sep 2013
- United States
- black & white illustrations