76 BULLETIN 139_, UNITED STATES NATIONAL MUSEUM 



Pottery furnishes its own enduring record, and it was, before the 

 modern discoveries of antiquity, probably known to Sir Thomas 

 Browne that shards were quite as imperishable as charcoal. '® 



Clay heated to 750° F. has driven out of it the water of combina- 

 tion and becomes incapable of softening by water This observation 

 is unexcelled as to antiquity, and due to be made at one time or 

 another by the earliest users of fire. Nevertheless, it was an im- 

 mensely long period before this knowledge had practical adaptation 

 in the formation of vessels or other objects of use. 



The presumed order of development is: Observation of the effects 

 of heat on the fireplace or surroundings, as clay margins, etc.; har- 

 dening of perhaps children's artifacts thrown in the fire; when fire 

 accidently or otherwise preserved the shape of clay-covered structures 

 of vegetal elements, as primitive daubed houses or vessels such as 

 the Mohave Indians of Arizona make, only suggestive; and the 

 actual making and firing for a definite purpose, the so-called discov- 

 ery. The wheel follows, beginning with rudimentary devices for 

 handhng the ware, and arrives at an effective machine. Gradually 

 also there is an increasing command of heat, and with selection of 

 clays stoneware is made, and so on through the history of ceramics.^" 



GLASS 



The history of glass making in respect to its bearing on the prog- 

 ress of our knowledge of nature covers a very interesting field. 

 Glass is one of the results of unconscious experiments, primarily giv- 

 ing rise to the observation of the effects of fire on various materials 

 happening to be subject to its action. These observations could 

 occur innumerable times in early periods before the next step toward 

 the utilization of the fused product could be taken. The advance is 

 made when the cultural stage demands it. Glass is foreshadowed in 

 the reduction of ores. Thus the manufacture of glass is recent when 

 compared with the time column. Popular belief in the discovery of 

 glass by the fortuitous presence of sand and niter in a beach fire is 

 led astray by fables invented to fit imaginary happenings. Long 

 before the discovery of glass the metallurgist was familiar with slag, 

 and the potter in an unusually hot fire sometimes produced the fore- 

 runner of glaze. Lava also was a practical demonstration of the sol- 

 vent power of fire well within the experiences of some of the groups 

 of primitive man. 



BATHS 



There is little data on the origin of the hot-air and vapor bath, 

 though there are many references giving the custom great antiquity 

 among civilized peoples.^' The distribution of the custom over wide 



» Sir Thomas Browne. Hydriotaphia. Works, p. 377. 



>o See Synoptic Series. Proc. U. S. Nat. Mus., vol. 60, 1922, p. 40. 

 i " Strabo. Book 3, chap. 3, par. 7, says that heated stones were used for the hot-air bath by the Lusi- 

 tanians and Lacedemonians. 



