Mr. Bevan on the Modulus of Elasticity of Gold, 445 



<licantur (fig. 14.). Abdomen ovatum, convexum.postice acuminatum. Pedes 

 longi, gracile^, femoribus crassioribus. — Emb. Ruddii, Westw. Niger, abdo- 

 mine nitido, pedibus piceis, femoribus tibiisquein medio obscurioribus ,• alis 

 subfuscescentibus. Long. Corp. If lin. Exp. alar. 3£ lin. Yorkshire, Rev. 

 G. T.Rudd. — Obs. Alarum nervi secundum typum Aly&iidarum disponun- 

 tur, at antennae caputque tuberculatum affinitatem cum Froctotrupidibus 

 quibusdam demonstrant. 



24. Hemisius, Westw. 

 Telenomo Hal. affinis. Caput thoracis fere magnitudine. Antennas in tu- 

 berculum parvum anticum positae, longae, ad apicem clavatae, articulis 

 11-discretis, 3tio, 2do minori, clava 4-articuIata (fig. 12.). Thorax con- 

 vexus, rotundatus; alas thorace toto vix longiores, ramo stigmaticali elon- 

 gato, clavato, in alas discum oblique descendenti. Abdomen ovatum, sub- 

 depressum, segmento 2do maximo. — Hem. minutus,V/ est. Niger, abdomine 

 piceo-nigro, pedibus flaveseentibus, antennis piceis basi pallidis. Long. 

 Corp. £ lin. 



The Grove, Hammersmith, April 24, 1833. 



LXXIV. On the Modulus of Elasticity of Gold. By B. Bevan, 



Esq. 

 To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 IT is something remarkable that while the modulus of elas- 

 A ticity and stiffness of a number of the common metals have 

 been investigated and determined, that of gold, which is con- 

 sidered the most valuable metal, should have been neglected, 

 or overlooked. To supply this defect I have lately obtained a 

 piece of pure gold, and have ascertained the measure of its 

 elastic force to be about 11,690,000 pounds to the square 

 inch, or 1,390,000 feet when recently drawn into wire, or 

 about 1,000,000 feet lower than the modulus of platinum, and 

 5,000,000 feet less than that of plate-glass. I suspect, how- 

 ever, that the modulus of gold as alloyed for coinage, is some- 

 thing higher than that of pure gold ; but at present I have not 

 been able to procure a piece of suitable dimensions to demon- 

 strate it. 



Those who are in the daily habit of taking gold coin soon 

 acquire a knowledge of the proper sound or note given upon 

 striking a piece of money upon a table or hard substance: this 

 well-known though undefined note or sound depends upon 

 the modulus of elasticity of the metal, as well as upon the dia- 

 meter and thickness. A piece of coin, of the same dimensions, 

 both as to diameter and thickness, of silver, will give a note 

 about a major fifth higher than one of gold, when a similar 

 coin of copper will give a note an octave above that of gold ; 

 and if made of steel would give a note a minor third above 

 that of copper. 



