392 POPULAR SCIENCE MONTHLY. 



illustrate the curious fact that the oyster has the hahit of forcing- 

 intruders out, not manlike through the door, but through the 

 walls of its house. The way of it is this : while the successive 

 coverings of nacre are deposited on the inside of the shell, the 

 outside of the shell is gradually decaying and crumbling away, 

 so that as the wall inside the alien object becomes thicker, the 

 part outside becomes thinner, till finally the intruder reaches the 

 surface — is literally forced through the shell of the oyster. 



The pearl is the one gem that comes to us perfect from the 

 hand of Nature, and to this its great antiquity as a gem is largely 

 due. Precious stones whose beauty and brilliance depend on pol- 

 ishing and cutting would naturally be discovered and utilized 

 later. The discovery of the diamond, for instance, probably dates 

 within historic times. Though known earlier, it was not gener- 

 ally included among the gem treasures of royalty even as late 

 as the seventh century. The modern cutting of diamonds in 

 regular facets was invented as recently as 1456. Indeed, it is 

 quite probable that the pearl was the first gem known and 

 treasured by prehistoric man — since the search for food must 

 have been the first occupation of the earliest of the race, and 

 the shining pearl would thus have been discovered in river mus- 

 sels if not in marine oysters. Certain it is that the Old Testa- 

 ment and the, most ancient written histories allude to pearls, 

 and that remoter evidence is found in the tombs and excavated 

 cities of still earlier eras. The Egyptians, Babylonians and As- 

 syrians held the pearl in an esteem verging on reverence. 



Not only were pearls known and prized as the most precious of 

 gems, but they were gathered and treasured in astonishing quan- 

 tities by the early Oriental potentates. Many relics and records 

 of those days remain. The crown of the Khan of the Tartars, 

 captured on the Oxus by the Persians in the fifth century, was 

 decorated with several thousand pearls. The famous crown of 

 Chosroes, made in the sixth century, and which was strangely 

 concealed for a thousand years in an obscure fortress among the 

 Lauristanian Mountains, till brought to light by Shah Abbas, is 

 incrusted with pearls in conjunction with rubies. In the seventh 

 century the Arabs captured from the Persian nobles fabrics of 

 amazing richness, among which was one marvelous carpet of 

 white brocade, four hundred and fifty feet by ninety feet, with a 

 border worked in precious stones to represent a garden of all 

 kinds of beautiful flowers — the leaves of emeralds and other 

 green gems, the buds and blossoms of pearls, along with rubies 

 and sapphires. 



The treasures of the Turkish nobility during some of the more 

 brilliant reigns of the empire seem to belong to fable rather than 

 to veritable history. Sinan Pasha, dying at eighty, left fifteen 



