4 LETTERS ON NATURAL MAGIC. 



trumpet notes scared the robber from the treasure 

 which it guarded; the speaking head which 

 uttered its oracular responses at Lesbos ; and the 

 vocal statue of Memnon, which began at the 

 break of day to accost the rising sun, were all 

 deceptions derived from science, and from a dili- 

 gent observation of the phenomena of nature. 



The principles of Hydrostatics were equally 

 available in the work of deception. The marvel- 

 lous fountain which Pliny describes in the island 

 of Andros as discharging wine for seven days, 

 and water during the rest of the year; the 

 spring of oil which broke out in Rome to wel- 

 come the return of Augustus from the Sicilian 

 war, the three empty urns which filled them- 

 selves with wine at the annual feast of Bacchus 

 in the city of Elis, the glass tomb of Belus 

 which was full of oil, and which when once 

 emptied by Xerxes could not again be filled, 

 the weeping- statues, and the perpetual lamps of 

 the ancients, were all the obvious effects of the 

 equilibrium and pressure of fluids. 



Although we have no direct evidence that the 

 philosophers of antiquity were skilled in Me- 

 chanics, yet there are indications of their know- 

 ledge by no means equivocal in the erection of 

 the Egyptian obelisks, and in the transportation 

 of huge masses of stone, and their subsequent 

 elevation to great heights in their temples. The 

 powers which they employed, and the mechanism 

 by which they operated, have been studiously con- 

 cealed, but their existence may be inferred from 

 results otherwise inexplicable ; and the inference 

 derives additional confirmation from the mechani- 

 cal arrangements which seemed to have formed 



