APPENDIX 591 



Method of Observation employed by the Author on the Summit of Mauna 

 Loa. My camp was placed near the middle of the west margin of 

 the crater about 13,500 feet above the sea. The instruments employed 

 were a Sixe's maximum and minimum thermometer made by Negretti and 

 Zambra, several unmounted thermometers, and a reference thermometer 

 (with a Kew certificate) by the above-named makers, which was used as a 

 standard. The freezing point was also tested for all the instruments on the 

 summit in melting powdered ice. The maximum air observations and 

 those on the relative humidity were taken in a small cave with a hole 

 in the roof, through which there was a steady flow of air. One day 

 was occupied in comparing the cave-observations with those obtained 

 under a temporary screen rigged up outside my tent, the only difference 

 shown being as a rule less than a degree. The minimum observations 

 taken in my tent, where there was no artificial heat, were usually only 1*5 

 higher than those given by a thermometer outside the tent. 



Results of the Observations on the Top of Mauna Loa, Aug. 9-31, 1897 



Mean minimum temperature of air in shade 23*2 F. 



Mean maximum 53-8 



Mean daily range of temperature 30*6 



Lowest reading 15-0 



Highest reading 6i'2 



Mean temperature for the period 38'5 



Mean relative hunudity, 8- 9 ,m, 44-5 ',. 



" ( are not given in 



6 P-m., 56 / o ) the register. 



On Aug. nth, at 10 a.m., wet bulb, 33*2 ; dry bulb, 52 ; difference, 

 18-8. 



On Aug. 1 9th, at n a.m., wet bulb, 357; dry bulb, 56 ; difference, 

 20-3. 



Owing to the varying winds at my camp, the relative humidity 

 fluctuated greatly in a short time. Thus, on Aug. 1 2 it was 46 / o at noon, 

 and 79 / at 2 p.m. 



Average Cloudiness (10 indicating a Sky completely Overcast] 



Cloudless during 12 out of 13 days 

 19 20 

 13 22 

 6 22 



17 22 

 II 12 



