126 



NATURE 



[Dec. 14, 187T 



The thermometers were under pressure for an average 

 time of 37 minutes in each experiment. 



May 6. — The following experiment was made with the 

 Hydrographic Office pattern (not used yesterday) for 

 comparison. Mr. Casella reading. 



Pressure^ 2,000 fathoms = 5,452 lbs. Under pressure 

 seventeen minutes. 



Second Series of Experiments 

 June 21. — The thermometers were placed in the 



cylinder, which was filled with water ; the supply-tub or 

 cistern for pumping in from, and a tub of water standing 

 near the press, were also filled and thus left all night. 



yiine 22. — A dull morning, with no sun, and all condi- 

 tions most favourable for observing. 



Before commencing, obtained two tubs of water with 

 12" difference of temperature, and tested the thermometers 

 as to time in taking up heat and contrariwise, and it was 

 found that, by allowing the thermometers to remain under 

 pressure eight minutes, the same results would be obtained 

 as if they were allowed to remain half an hour or more, 

 as in the first series of experiments. 



The thennometers used were — 



Dr. Miller's pattern. 

 Hydrographic Office pattern. 



Encased (Sir William Thom- 

 son's design). 



Second Series of Experiments. Errors at different pressures. {Abridged from original.) 



The thermometers were under pressure eight minutes in 

 each experiment. 



The mean difference for each 250 fathoms by each 

 thermometer is as follows {abridged) : — 



By First Series of Oisservations 



Bv Second Series of Observations. 



supplying the cylinder, that for any delicate observation 

 the conditions were not favourable ; the observations for 

 calorific effect were therefore delayed until the weather got 

 colder, when a more equable temperature could be ensured 

 throughout the experiment. 



In order to ascertain what time it would require for 

 these instruments to take up temperature (as it was of im- 

 portance they should not be kept under pressure longer 

 than necessary) observations were made for the purpose, 

 and it was found that five minutes would be sufficient 

 time for the Thomson thermometers to take up the most 

 minute portion of heat observable. 



November 12. — The following observations were made 

 day cloudy, all the conditions favourable. 



No. I. Pressure = 2,500 fathoms = 6,8i7lbs. Under 

 ten minutes. 



Experiments for Calorific Effect. 



The Phillip's encased maximum thermometers (Thom- 

 son's) being entirely protected from any eftect by com- 

 pression, it was decided to ascertain by their means the 

 calorific effect produced by the sudden compression of the 

 water in the cylinder ; but, as in the two series of experi- 

 ments recorded, there was such a gradual increase in the 

 temperature of the air and also in the water used for 



Experiment No. 2 (same pressure), 

 twenty minutes. 



Under pressure 



