216 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



On the loth of September, at 12 o'clock, the temperature in the basin 

 of the Grand was 189° F. The basin was full and receiving some of the 

 overflow of the Turban. This temperature is practically the same as that 

 taken in 1872 (188° F.). No temperatures were taken immediately prior 

 to the eruption, but there is no doubt that it is higher then than at other 

 times. 



Turban Geyser (Plate XXI). — Although one of the minor geysers of 

 the Upper Basin, it has attracted considerable notice from its connec- 

 tion with the Grand, and from its peculiar crater, which is well shown 

 in the illustration. It was named in 1872 from the fancied resemblance 

 of some of the large globular masses in its basin to a Turkish head- 

 dress. These masses are irregular in form and size, and are found around 

 the rim as well as in the bottom of the basin. They are yellow, and 

 some look like squashes or pumpkins. 



The Turban and Grand are on the same platform of deposit, the former 

 being raised about 3 feet above the latter. The basin of the Turban is 

 irregularly quadrangular in form, 23 feet in length and 11 feet wide. 

 The depth is 6 feet. The geyser orifice is at the north end, and is very ir- 

 regular in shape, measuring 3 by 4 feet. Preceding the eruption the water 

 rises and fills the basin, and after the action ceases it sinks in the tube 

 very rapidly, leaving the basin entirely empty, as shown in the illustra- 

 tion. During the erujjtion it is violently agitated, and the mass is so 

 large that the height attained is not great, the water being splashed out 

 irregularly in all directions. Surrounding the Turban are shallow pools 

 with ornamented rims. 



No observations were made in 1871 other than to note the form of the 

 basin. 



1872.— The following are the notes taken in 1872: 



August 20. — 6.58 a. m., spurts for three minutes, attaining a height ot 

 25 feet. 7.5.30 a. m., spurts again, lasting 15 seconds, height only 10 feet. 

 Two and a quarter minutes later the basin is empty. Thirty -four min- 

 utes after, steam escapes and the water rises. 7.32.30 a. m., small spurts. 

 7.37 a. m., spurts, the maximum height being 22 feet. 7.44 a. m., the 

 basin is full and water overflowing into the Grand. 



In this eruption, or rather in the two eruptions, which are separated 

 by a period of 26 minutes and 45 seconds, we cannot determine much as 

 regards the interval. The first began 2 minutes after the second period 

 of the Grand began, i. e., 25 minutes after tbe beginning of the first period, 

 and lasted 45 seconds longer tlian the end of the eruption of the Grand. 

 The second began 27^ minutes after the Grand had finished its eruption. 

 This would appear to indicate independence in action. 



The steam vent spurted steam and water at 7.38 a. m,, ^. e., while the 

 Turban was in action, and after the Grand had subsided. It was in 

 action before the latter, and while the two were in aciiou simultaneously 

 it was quiet. The Turban was not observed during the first and second 

 eruptions of the Grand, as they occurred early in the morning, and we 

 were in camp across the river. 



1873. — Professor Comstock saw the Turban in action during the eruj)- 

 tion of the Grand. His description agrees closely with the erui)tiou 

 noted by myself in 1872. He says : 



Shortly before an eruption, as is common in the geyser basins, the water rises so as 

 to fill the pit. At 4.09 p. m., August 25, duiiug one of the spoutings of the Grand 

 Geyser, the water in the Turban was agitated, boiling up in a powerful throb to a 

 height of i> feet, with occasional protracted spurts varying from 20 to 30 feet. At 4.12.5 

 the water receded far down the subterraneous passage; at 4.17 p. m. vapor ascended, 

 followed by water at 4.17.5, after which the agitation was variable in degree, being con- 

 tinued without interruption nntil 5.40. Frequently during the eruption quantities of 



