228 REPORT UNITED STATES GEOLOGICAL SURVEY. 



Eruptions Nos. 1 to 10, inclusive, were noted by Dr. Hay den. 



Eruptions Nos. 49 to 55, inclusive, and Ko. 57 were noted by Mr. 

 Eichardson. 



Eruptions Ii^os. 59 to 67, inclusive, were noted by Mr. Eccles. 



Eruptions Nos. 69 to 77, inclusive, were noted by Mr. Ladd. 



The heights given by Mr. Ladd are perhaps a little too low. It is 

 somewhat difficult to obtain the exact height unless one has been accus- 

 tomed to distinguish between the steam and column of water. 



The heights in all cases represent the distance from the top of the 

 crater to the top of the column. They were measured with the gradi- 

 entor, which is the reason so few comparatively were taken, as the in- 

 strument was frequently in use for the topographical work. The dura- 

 tion is from the beginning until the escape of steam alone shows that 

 the water period is over. The duration of some is not given as our dis- 

 tance from the geyser at times prevented our obtaining it. The aver- 

 age duration of the steam period, as determined from 5 observations, is 

 60 seconds. 



Four of the intervals given in this table are below 60 minutes and 

 eight over 70 minutes, the range being from 64 minutes 4 seconds to 78 

 minutes. Neither the long nor the short intervals occur with any reg- 

 ularity, nor do they appear to influence the duration of the eruption. 

 The greatest and the smallest elevation of the column have nearly the 

 same duration. The twelfth eruijtion had a duration of 4 minutes and 

 25 seconds, and the column reached the height of 135 feet, while the 

 seventy-first eruption reached a height of only 88 feet and had a dura- 

 tion of 4J minutes — just five seconds longer. The shortest duration was 

 3 minutes and 40 seconds on the twenty-sixth and fifty-sixth eruptions, 

 and the height of the column was 106 feet in the former. The longest 

 duration was 5^ minutes, but no height taken ; but in the seventy -third 

 eruption the duration was 5 minutes and the height of the column was 

 110 feet. These heights were all carefully taken to the top of the column 

 of water, and are the heights above the top of the cone. At no time 

 was the crater observed to be full of water, and immediately after the 

 eruptions the water sinks or disappears and steam escapes. There is 

 not, however, the violent steam period that is noted in the Castle ; the 

 steam from Old Faithful escapes very gently after the column sinks. 



The fifty-sixth eruption noted in the table above occurred August 30, 

 at 6.30 p. m. At 5.30 p. m. the crater was visited and found entirely 

 empty. Steam was coming gently from the orifice about 5 feet down in 

 the crater and the maximum thermometer held in this registered 199° F. 

 At 5,50 p. m. water began to spurt into the crater with puft's of steam 

 and the temperature registered was 200° F. These sijurts became higher 

 and higher until they splashed over the side of the crater. They also 

 came closer together, and at 5.56^ p. m. spurted 5 feet above the top. 

 Five temperatures were taken, all being 200° F. The last one was just 

 four and a half minutes before the eruption began. The pools outside 

 just after the eruption had a temperature of 170° F. This was the water 

 that had fallen from the column and had been cooled by contact with 

 the air. The theoretical boiling point here is 199°, so that we have a 

 temperature above the boiling point caused, probably, by the heating of 

 the water during the escape of the superheated steam from far down in 

 the tube of the geyser. It was impossible to obtain the temperature of 

 the water while the geyser was in action, but it was probably greater 

 than 200°. 



1879. — Mr. I^Torris, the superintendent of the Park, thinks that the in- 



