534 POPULAR SCIENCE MONTHLY. 



oping a pure duodecimal system, combined the seximal with, the 

 decimal in a multiplicative manner, and so developed a sexagesi- 

 mal system. 



The reader may take his choice between these two attempts to 

 explain what, in any case, must be regarded as a remarkable phe- 

 nomenon. Without denying that either may possibly be the true 

 explanation, the writer is of the opinion that much additional 

 evidence will be required to finally solve the question. With the 

 rapid advance that is now being made in the field of Babylonian 

 antiquities it is not impossible that the needed information will 

 be forthcoming. 



IVORY: ITS SOURCES AND USES. 



BY N. B. NELSON. 



ripHOUGH an animal product, its combinations with wood, 

 JL particularly ebony, from the earliest history, and the simi- 

 larity of its uses and working in the way of carving, turning, 

 veneering, and inlaying, make ivory an interesting material to 

 joiners, decorators, and builders. 



In texture, elasticity, hardness, peculiar markings or cloud- 

 ings of the grain, and several other particulars, ivory is very like 

 the harder woods, and, being of similar durability, is very suit- 

 able to " make up " in mosaics, inlaying, etc., with them, making 

 a companion commodity. 



Ivory is really dentine that substance, not unlike bone, of 

 which teeth principally consist. By usage it is restricted to the 

 dentine of those teeth which are large enough for industrial pur- 

 poses viz., the tusks of the elephant, hippopotamus, walrus, nar- 

 whal, and some varieties of whales. These forms of ivory differ 

 about as the hard woods differ : the elephant ivory, by its size 

 and quality, is best suited for all purposes; that of the hippo- 

 potamus is harder and finer, but owing to its hollowness can 

 only be used for small articles. The old Norsemen used exten- 

 sively the tusks of the walrus, and when " whaling " was at its 

 best the sperm whale was sought almost as much for the ivory as 

 for the oil. It was the writer's fortune to examine a whale's tooth 

 which was nine or ten inches in length and six or eight in cir- 

 cumference, and seemed solid ivory of a beautiful quality, but so 

 hard as to defy every effort of its owner, who was an expert 

 carver, spoiling, as he expressed it, his " tools and temper." 



Ivory, consisting chemically of an organic matrix or growing 

 element, phosphate and carbonate of lime, is permeated by nu- 

 merous exceedingly fine canals, starting from the organic or pulp 

 cavity and running generally outward to the circumference of 



