214 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



The total duration, if the time of ending is 5.47 p. m., as published, is 1 

 hour and 46 minutes. I think, however, that this should be 4.57 p. m., as 

 Professor Comstock speaks of its spurting several times, and gradually 

 increasing in power during the last period (58 minutes). If it is 4.57 

 the total duration would be 56 minutes, which is a little longer than 

 has been previously observed. There are, however, four periods, which 

 may account for the greater length. As observed in 1872, the longer 

 period is the last. 



1874. — Dunraven did not witness an eruption of the Grand. 



1875. — Dana and Grinnell describe an eruption witnessed by them as 

 follows : 



The height of the first discharge did not much exceed 100 feet. It rose to this point 

 in a series of violent pulsations, remained at this altitude for 3 or 4 minutes, and then 

 sank back into the pool, which became quite still. A moment later it had commenced 

 again, the water rising certainly 150 feet by estimate. This again sank down, and 

 again rose to its maximum height, and this was twice repeated. * 



Captain Ludlow, speaking of this eruption, says : 



Meanwhile the neighboring geyser [Turban] was splashing its waters in all direc- 

 tions aud discharging clouds of steam, while a steam vent close at hand kept up a most 

 outrageous roar, t 



Only one eruption appears to have been witnessed by the party, so 

 that nothing was noted in regard to the interval of the geyser. 



The maximum was attained in the third period, as in the case of the 

 eruption observed by Professor Comstock in 1873. 



The data are not sufficient to give the lengths of the periods for com- 

 panson with the other eruptions already noted.f 



1878. — Six eruptions were noted during the season, four occurring 

 during our first visit and two during the second They were noted from 

 a distance, the heights being taken from a base line of 2,500 feet. The 

 following are the eruptions : 



First eruption^ August 21. — Eruption began 3.55 p. m.; duration, 14 

 minutes 45 seconds. 



Second eruption^ August 28. — Eruption began 11.26 a. m. ; duration, 16 

 minutes. 



Third eruption., August 29. — Eruption began 4.14 p. m. ; duration, 18 

 minutes 45 seconds. 



Fourth eruption., August 30. — Eruption began 9.09 a. m. ; duration, 11 

 minutes 30 seconds. 



Fifth eruption, September 9. — Eruption began 10.15 p. m. ; duration 

 not taken. 



Sixth eruption, September 10. — Eruption began 8.15.30 j). m.; duration 

 15 minutes 20 seconds. 



The following are the intervals between the beginnings of eruptions : 



Between first and second eruptions, 19 hours 32 minutes. 



Between second and third eruptions, 28 hours 48 minutes. 



Between third and fourth eruptions, 16 hours 55 minutes. 



Between fifth and sixth eruptions, 22 hours 00 minutes 30 seconds. 



* Eeconnaissance from Carroll, M. T., to Yellowstone National Park, &c., p. 131. 



+ [hid, p. 27. 



X In 1881 Colonel Gregory, with General Sheridan's expedition, saw an eruption of 

 the Grand with 8 distinct spoutings, the total time of the eruption being 22 minutes. 

 {See page 21 of General Slwfidan^s report.^ 



