OF TJEEA Am) UEINAET WATEE. 
803 
somewhat fewer intermissions; and there have been fewer experiments, which might 
interfere somewhat with the regular nutrition of the system. The summer holiday was 
again taken, and a month was again spent at the sea-side. The only important condition 
of contrast refers to the frequency of the analyses of urea ; for, whilst in the former year 
there were always three, and often more analyses daily, with a view to determine the excre- 
tion at the different periods of the day, in the latter there was but one daily. Hence in 
the past year it has not been possible to restrict the day to uniform hours, viz. from 8 a.m. 
as before, since, without knowing the rate of excretion proceeding m the night, no correct 
addition or subtraction of quantities could be made for defect or excess of time. The 
twenty-four hours has therefore terminated at periods from 8 to 9|a.m., but commonly 
it ended at about 8^ a.m. ; and the addition and subtraction has been made by the average 
rate of emission of the twenty-four hours. The former was doubtless the more correct 
method ; but the latter, by not reducing the day to a uniform hour, has not introduced 
any material error. It must also be recorded that, as there are errors of inquiry con- 
nected with Liebig’s analysis for urea (as indeed with all other inquiries), they have been 
varied by the reduction of the number of daily analyses. I am not able to state 
whether this has rendered the total computation of the daily excretion more or less 
correct, since it is not known in what direction the errors in the analyses lie, or whether 
the direction is the same with different inquirers ; but, considering that it lies in the 
appreciation of the exact degree of colour in the test solution, and knowing the degree of 
care which I have taken, I am inclined to believe that the tendency in my hands would 
be to lessen the quantity as the experiments w'ere fewer. 
Meteorological conditions . — The former year was remarkable for its cold summer 
and the long-continued frost of winter, whilst the latter, without being a hot year, 
was warmer in both summer and winter. Each year comprehends a part of two 
cold seasons, and the summer season, since it begins at the middle of March. The 
average temperature of the latter year was 2°‘2 higher than that of the former. With 
the exception of May and September, February and March, the monthly temperature 
was higher; and the difference in May was only a defect 0°'4. The increase of tempera- 
ture was particularly found in June, July, August, and October, in which the average 
monthly increase was 4°-4, 3°T, 5°-6, and 4°-3 respectively. The highest mean daily 
temperature was 9°-8 higher, and the lowest mean daily temperature was 6°'8 higher, in 
the latter than in the former year on the days of inquiry. The pressure of the atmo- 
sphere was also somewhat higher in the latter than the former year, the excess being 
•033 inch. The monthly averages on the days of inquiry were higher, except in July, 
September, October, February, and March ; and the increase was particularly found in 
April, May, August, and December, in the last of which it was ‘450 inch. The most 
marked months of defect were September and March. As we have shown that the 
opposition in the movements of these two elements of season have an important influence, 
it may be remarked that the two years corresponded in April and July, but differed in 
MDCCCLXI. 5 Q 
