158 SOAPING GEYSERS. 



point of tlie thermal waters from the springs, were determhied from 

 actual experiments by heating over a lire, employing every possible 

 precaution to avoid sources of error. Surface waters and deep-seated 

 mineral waters gave the same results, and coiucided with the calcu- 

 lated boilingi^oint at this altitude. Hundreds of observations have 

 been carefully taken where the waters in the active and running 

 springs boiled at temperatures between 198° and 199o F. 



As will be shown later in this paper, the thermal waters are solu. 

 tions of mineral matter too dilute to be affected to any appreciable 

 extent as regards their boiling-point by their dissolved contents. The 

 theoretical boiling-point for the springs and pools in the Upper Geyser 

 Basin may be taken at 92.5° 0. (198.5 F.). In many of the large cal- 

 drons, where the water remains quiet, a temperature has been recorded 

 of 94° C. (201.2° F.) without the usual phenomena of boiling. This 

 gives a body of super-heated water, with a temperature at the surface 

 1.5° 0. (2.7° F.) above the point necessary to produce explosive action. 

 Thermometers plunged into the basins show slightly varying tempera- 

 tures, dependent upon their position in the basin. They indicate the 

 existence of numerous currents, and a very unstable equilibrium of 

 the heated waters, which are liable, under slight changes, to burst 

 forth with more or less violence. It is under these conditions that geyser 

 action can be accelerated by artificial means. If into one of these 

 super-heated basins a handful of sinter pebbles be thrown, or the sur- 

 face of the water be agitated by the rapid motion of a stick or cane, 

 or even by lashing with a rope, a liberation of steam ensues. This is 

 liable to be followed by a long boiling of water in the pool, which iu 

 turn may lead to geyser action. There is some reason to believe that, 

 at least in one instance, an eruption has been brought about by a violent 

 but temporary gust of wind, which either ruffled the water or disturbed 

 the equilibrium of the pool, and changed momentarily the atmospheric 

 l^ressure. 



In Iceland travellers liave long been accustomed to throw into the 

 geysers turf and soft earth from the bogs and meadows which abound 

 in the neighborliood, the eftect produced being much the same as tliat 

 of sinter pebbles and gravel upon the geysers in the National Park. 

 So well was this understood that at one time a peasant living ueiU' the 

 Iceland locality kept a shovel solely for the accommodation of those 

 visiting the geysers. 



In my letter to Dr. Ilaymond 1 mention the curious fact that the 

 Laundryman's Spring, now known as the Chinaman, in which geyser 

 action may most easily be produced by artificial means, has never been 

 regarded by the Geological Survey as anything but a hot spring, and 

 ]io one has ever seen it in action without the application of soap, ex- 

 cept in one instance, when it was made to ])lay to a height of 20 feet 

 after stirring it vigorously with a pine bough for nearly ten minutes. 

 In our records it is simply known as a spring. 



