MAUNA LOA. 153 



steward was also attacked with severity, and several of the men ; but, 

 by aid of the remedies given us by Dr. Judd, the next morning found 

 us all much relieved. 



The dew-point could not be obtained with Pouillet's hygrometer (a 

 capsule). Whenever this was the case, electricity was found to be 

 easily excited : on moving any articles of dress from the person, it 

 would develope itself in sparks. On examination, it was found that 

 our pulses varied during the day, and were very easily excited. Dr. 

 Judd's fluctuated from sixty to one hundred beats, Mr. Eld's from 

 eighty-four to one hundred and twenty, and mine from seventy-two to 

 one hundred and eight. 



The night was favourable for observations, and we succeeded in 

 making many. The wind was from the northeast. The thermometer 

 at sunrise was at 20°. The sun did not rise clear, as I was in hopes it 

 would have done, so as to afford me an opportunity of again seeing the 

 refraction, and measuring it. 



The 3d proved fine, and the pendulum-clock and apparatus being ar- 

 ranged and adjusted, the clock was put in motion, and a comparison 

 made with the three chronometers every two hours. 



It being Sunday, and a fine day, the men were allowed to wander 

 about the crater ; and some descended into it, bringing back many fine 

 specimens of lava. 



During our stay on the summit, we took much pleasure and interest 

 in watching the various movements of the clouds ; this day in par- 

 ticular they attracted our attention ; the whole island beneath us was 

 covered with a dense white mass, in the centre of which was the 

 cloud of the volcano rising like an immense dome. All was motion- 

 less, until the hour arrived when the sea-breeze set in from the 

 different sides of the island: a motion was then seen in the clouds 

 at the opposite extremities, both of which seemed apparently moving 

 towards the same centre, in undulations, until they became quite 

 compact, and so contracted in space as to enable us to see a well- 

 defined horizon ; at the same time there was a wind from the moun- 

 tain, at right angles, that was affecting the mass, and driving it 

 asunder in the opposite direction. The play of these masses was 

 at times in circular orbits, as they became influenced alternately by 

 the different forces, until the whole was passing to and from the 

 centre in every direction, assuming every variety of form, shape, and 

 motion. 



On other days clouds would approach us from the southwest, when 

 we had a strong northeast trade-wind blowing, coming up with their 

 cumulous front, reaching the height of about eight thousand feet, 

 vol. iv 20 



