Note 9 — Chapter I

In another experiment (No. 37), Hero shows “how temple doors may be opened by fire on an altar.” He says, “Let the proposed temple stand on a pedestal, on which is also a small altar. Through the altar insert a tube, of which one mouth is within the altar, and the other nearly at the centre of a globe. The tube must be soldered to the globe in which a bent syphon is placed. Let the hinges of the doors be extended downwards, turning freely on pivots, and from the hinges let two chains running into one be attached by means of a pulley to a leaden weight, on the descent of which the doors will be shut, let the outer leg of the syphon bend into a suspended vessel and fill the globe half full of water. When the fire becomes hot, the heated air in the altar expands and, passing through the tube into the globe, will drive the liquid through the syphon into the suspended vessel which, descending by its weight, will tighten the chains and open the doors.”