June 1, 1895.] 



KNOWLEDGE 



121 



AN ILLUSTRATED 



MAGAZINE OF SCIENCE 



SIMPLY WORDED-EXACTLY DESCRIBED 



LONDON: JUNE 1, 1895. 



CONTENTS. 



The Coinage of the Greeks. Bj G. F. Hill, M.A. 



{Ilhistratecl) 



Colour-Producing Bacteria. ByC.A.MiTCHELL.B.A.Oxon. 

 The Giant Birds of South America. By R. Lydekker, 



B.A.Cantab, F.E.S. {Illustrated) 



The Colours of Butterflies. By C. F. Mahishall, M D., 



B.Sc, F.B.C.S. ... " 



Science Notes 



The Suns Stellar Magnitude. By J. E. Goee, F.B.A.S. 

 The Sun Pillar. BytlieRev. SAMnELBAEBEE. {Illustrated) 

 The Progress of Selenography. By Akthfs Mee, 



F.R.A.S. (Illustrated) 



Lettei»s :— Datid Flaneey; J. Plassmann; E. E. Maek- 

 \viCK; C. E. Peek; Aethub Paket, B.A.; (Miss) F. 



Stephens 



Notices of Books 



The Functions of the Hairs of Plants. By .T. Pextlanb- 



Smitr, M.A., B.Sc. {Illustrated) 



Some Recent Patents. {Illustrated) 



The Face of the Sky for June. By Heebert 



Sadler, F.B.A.S 



Chess Column. By C. D. Loooce, B.A.Oxou 



121 

 124 



125 



128 

 129 

 130 

 132 



133 



135 

 137 



138 

 142 



142 

 143 



THE COINAGE OF THE GREEKS. 



By G. F. Hill, M.A. 



BY a coin is usually understood a piece of precious 

 metal (as a rule gold, silver, or copper) of a size 

 and shape convenient for handling, and marked 

 with some stamp to' guarantee its genuineness 

 and save the trouble of continually calculating its 

 value. In the days before the invention of money, 

 exchange had been carried on by a process of barter, so 

 much of an article offered being exchanged against so much 

 of an article required. But it was naturally found convenient 

 to agree upon a medium having some intrinsic value, and 

 not liable to excessive fluctuations, which would always be 

 desirable, and would, therefore, be accepted at all times by 

 all parties. As early as the seventh century before Christ 

 in Asia Minor, and, perhaps, even earlier in the far East, it 

 was found that the most practicable medium was a precious 

 metal divisible into small quantities, each of which would 

 be equivalent in worth to comparatively large quantities of 

 other articles of commerce. In earlier times we find 

 various other things, more or less clumsy, employed as 

 measures of value. For instance, over a great part of the 

 world, the unit in terms of which other articles were 



valued was the ox. A less bulky unit is the cowry-shell, 

 used even at the present day in some parts of Africa, where 

 the employment of metal for this purpose is impossible or 

 has not been thought of. The traces of such customs long 

 remained, being, perhaps, most marked in the conservative 

 Chinese Empire, where pieces of metal in the shape of 

 small knives or spades long continued to circulate, or in 

 Burma, where coins are still cast in imitation of shells. 



Coinage then, properly speaking, begins with the use of 

 small pellets or lumps of metal of fixed weight ; and that 

 these may be plainly stamped, they have to be of a 

 somewhat flattened form. This is the shape of the earliest 

 coins of Greece or Asia Minor which have come down to 

 us. The blank of metal, being placed (often in a heated 

 state) on an anvil, was struck with a stamp. A design let 

 into the anvil left its impression on the lower side of the 

 blank (generally called the obverse), while the upper (or 

 reverse) side was marked by the stamp. The latter instru- 

 ment was at first left undecorated (Fig. 1), but was after- 

 wards elaborated until the reverse design became nearly as 

 important as the obverse. The ancients seem to have 

 always used bronze for their dies, and as this soft material 

 easily wore out, the dies had constantly to be recut. The 

 result was an enormous variety in design, and it is rare to 

 find two ancient coins from the same die. Neither did 

 they use a collar to confine the metal, which, consequently, 

 was liable to spread irregularly in the striking, sometimes 

 to splitting-point. And the fact that the striking was done 

 by hand accounts for the frequent occurrence of what are 

 called double-struck coins, when the second blow brought 

 the stamp down in a different place' from the first, or the 

 coin had shifted between whiles on the anvil. 



The fabric of Greek coins went through a steady process 

 of development. The earhest blanks were of a somewhat 

 dumpy oval shape — in fact, resembhng a bean in form. 

 But by the beginning of the fifth century a flatter and 

 rounder shape had become almost universal. The 

 impression made by the stamp, the head of which was 

 square or oblong, or a combination of two or more of these 

 shapes (see Fig. 1), now sank deep into the blank, and a 

 raised border was thus left round the design. With time 

 the depth of the ineuse decreased, and towards the end of 

 the fifth century we find the incuse square often replaced 

 by an incuse circle, or entirely disappearing. After about 

 890 B.C. it may be said to be almost entirely absent, save 

 when for some reason a few cities revived it on their issues 

 at a much later period. The stamp, however, which was 

 now generally circular, naturally continued to produce a 

 more or less concave field on the reverse of the piece. In 

 the third and second centuries the flattening and spreading 

 of the coins was carried still further, but never so far as 

 to destroy the strength and solidity of fabric which makes 

 a coin satisfactory to handle. The bronze coinage which 

 begins in the fourth century is, like the silver of earlier 

 times, thick and dumpy at first, but soon yields to the 

 general tendency and becomes flat and spread. 



It is curious that the material used by the people to 

 whom the invention of money is attributed— the Lydians, 

 a wealthy and powerful race of Asia Minor— is neither 

 gold nor silver, but a mixture of the two. This mixture, 

 which is called electrum, was found in a natural state in 

 the district inhabited by them, and its adoption is there- 

 fore easily understood. Its value in relation to silver was 

 supposed to be about ten to one, while the proportional 

 value of gold to silver was in the less convenient ratio of 

 13i ; 1. As a matter of fact, modern analysis has proved 

 that the amount of gold in electrum coins varies very 

 considerably; but a rough proportion was probably 

 sufficient for the times. Electrum, however, was not 



