Reports from the 'Challenger? 



I. "Preliminary Report to the Hydrographer of the Admiralty 

 on some of the Results of the Cruise of H.M.S. ' Challenger ' 

 between Hawaii and Valparaiso." By Professor Wyville 

 Thomson, F.R.S., Director of the Civilian Scientific Staff on 

 Board. Received February 26, 1876. Bead March 23. 



[Plates 15-19.] 



To Capain Evans, C.B., F.R.S. 



Sir, — I have the honour to report that we left Honolulu on the 11th 

 of August, and on the 12th we sounded in 2050 fathoms, and took a 

 series. of temperature observations between the islands of Oahu and 

 Hawaii. At night a crimson reflection was visible in the position of 

 the top of Mauna Loa ; but as we understood that the side crater of 

 Kilauea only was in eruption, we supposed that that was some great 

 conflagration of forest on the flank of the mountain. All the following 

 day we steamed against a head wind along the rugged and picturesque 

 coast of Hawaii — headlands of lava and volcanic ash separated by deep 

 wooded ravines or " gulches," with a rapid hill-stream running in the 

 bottom of each. The top of Mauna Loa was covered with clouds 

 during the day ; but at night a splendid crimson glare hung over the 

 mountain, and lit up the clouds to a wide radius, and it became evident 

 that we were fortunate enough to see one of the rare eruptions of the 

 summit crater. Early on Saturday we cast anchor in Hilo Bay ; and a 

 party of us made arrangements to start as early as possible for the 

 volcano of Kilauea thirty miles distant, intending, if the eruption of the 

 summit crater continued and if we found it practicable, to push on to 

 the top of the mountain. "We left Hilo in the afternoon, taking mag- 

 netic and photographic instruments with us, and rode all night through 

 the forest and over the lava-flows, reaching the rest-house at the side of 

 the crater of Kilauea early in the morning. During the early part of 

 the night the light from the summit crater was very brilliant, but it be- 

 gan to pale soon after midnight ; and when we arrived at Kilauea we 

 found that the column of smoke at the top of the mountain had almost 

 entirely disappeared, and that the eruption was virtually over. This 

 was no great disappointment to us ; for we had learned that the ascent of 

 the upper peak could not be undertaken with reasonable safety without 

 much greater preparation in the way of provisions and warm clothing 

 than we bad had time to make, and we should have been obliged to give 

 up the idea in any case. In the afternoon we went down into the 



vol. xxiv. 2 M 



