128 



NATURE 



[Dec. 14, 1 871 



lead weight attached to the line before it ; and with re- 

 peated trials at full speed not the slightest difference cnuld 

 be detected. 



The error of the Miller-pattern thermometer as deduced 

 from the observations (some rejected in forming the mean), 

 abridged : - 

 Error per 250 fathoms as shown by hy- „ 



draulic press o-i6i mean 



Deduct for calorific effect .... '018 



True error for 250 fathoms .... o'i43 

 True error for 2,500 fathoms . . . i'43 



Mean Errors of Hvdiographic Office pattern Thermo- 

 meters, by testing-apparatus, corrected for calorific 

 effect : — 



The Progressive Rate of Error of the Hydrographic 

 Office pattern Thermometers, as deduced from the fore- 

 going table, by testing-apparatus, is by Casella, equal to 

 an increase of effect at the rate of o°-oi4 per 250 fathoms' 

 pressure ; and by Pastorelli, equal to a decrease of effect 

 at the rate of 0° 044 per 250 fathoms' pressure. 



Thus, while one set of thermometers show an increase 

 of effect under pressure, the other set denote a decrease, 

 and the mean of the two would be so small a decrease as 

 not to be appreciable ; and the practical conclusion is, 

 that, by the testing-apparatus, the elasticity of the glass is 

 in exact proportion to the pressure applied. 



Ocean Observations by Staff-Coiimander 

 E. K. Calver 



Although from the result of the experiments with the 

 testing app.aratus. a scale could be formed for the correc- 

 tion of the Hydrographic Office pattern thermometers, 

 that scale may be said to be made under theoretical 

 conditions rather than practical, and as it was necessary 

 to verify its correctness by observations in the ocean, 

 a number of the instruments used in the press were sent 

 on board the Porcupine in 1869, and a series of most 

 carefully taken observations were recorded by Staff-Com- 

 mander Calver at the same depths as the calculated pres- 

 sure applied in the press. 



It is unnecessary to give the details of these observa- 

 tions ; it will suffice to give the progressive error derived 

 from the mean of them, and corrected for the error of the 

 standard. 



The progressive rate of error derived from the above is 

 by Casella, equ;il to a decrease at the rate of 0-13 per 

 250 fathoms, and by Pastorehi, equal to a decrease of 

 effect at the rate of 0-09 per 250 fathoms. 



This result, contrary to that by the hydraulic press, 

 proves that the elasticity is not regular or in ratio to the 



pressure, but that after continuing regular up to a pressure 

 of 1. 000 fathoms, it decreases in a compound ratio to a 

 pressure of 2. coo fathoms, when its elasticity nearly ceases. 

 Comparison of the Hydrographic Office pattern Ther- 

 mometers as found by the hydraulic testing-apparatus and 

 by the Ocean Observations : — 



Casella. 



7-392 

 8-199 

 9-638 



r at 2,500 fathoms by the means 



Per 250 fathoms. 



By this comparison, although the errors, as found by 

 the two modes of observation, differ at individual depths 

 or pressure, still the means of Casella's per 250 fathoms 

 are almost the same, and those of Pastorelli's differ only 

 three-tenths of a degree in 2,000 fathoms, the extent to 

 which the comparison can be made. 



There can be httle doubt that, without the aid of the 

 Miller pattern, by an extended series of observations a 

 scale could have been obtained to correct the Hydro- 

 graphic Office pattern to a very close approximation of the 

 truth (in accordance with the proposed first intention of 

 the experiments) ; but the timely suggestion of Dr. Miller 

 has quite set at rest any difference of opinion as to the 

 instrument for future use. 



OYSTERS IN IRELAND* 



T T IS Excellency the Lord Lieutenant of Ireland having 

 •'■ ■'■ had represented to him that the artificial propa- 

 gation of oysters was imperfectly understood in Ireland, 

 appointed in October 1S68 Messrs. Blake, M.P., Francis, 

 Hart, and Brady, commissioners to inquire into and re- 

 port on the artificial cultivation and propagation of oysters. 

 The instructions to the Commission were to visit the 

 principal places in France, England, and Ireland, where 

 oyster cultivation is or can be carried on, to examine the 

 best authorities on the subject, and to ascertain as far as 

 possible the causes which have led to failures. It was 

 also hinted that three weeks would suffice for Ireland, a 



"■ Report of the Commission appointed to inquire into the Methods of 

 Oyster Culture in the United Kingr'om and France, with a View to the 

 Introduction of improved Methods of Cultivation of Oysters into Ireland. 

 (Presented to both Houses of Parliament bv command of Her Majesty.) 

 Dublin, 1870. 



