106 B. A. Gould—Algebraic Expression of the 
during a sufficient period to permit the form of the daily 
curve of temperature to be deduced independently. These 
are Buenos Ayres, where there were but two additional hours 
of observation ; Bahia Blanca, where the different hours, though 
comparatively numerous, were at different dates; and Cordoba, 
where the series of hourly observations comprises but a small 
number of years. And moreover, those hours, which it has 
een found necessary to adopt for the regular observations 
made for this office in the various parts of the Argentine 
territory, are not those which permit an exact determination of 
scientific value; and in addition to all these, the curvature in 
the vicinity of the maxima and minima is so gentle that a very 
considerable error as to the moment of their occurrence is pro- 
ductive of but comparatively slight influence upon the form of 
the computed curve, or upon other values which are determined 
through their agency. 
we neglect the variable terms beyond the third, we shall 
have from the mean of observations made at any of our sta- 
tions at 7 A. M., 2 P. M., and 9 P, M. during a given interval, 
the three equations 
(1) T,=M-+asin ( 7°+A)+6sin (14°9+B) +esin (212 +0) 
(2) T,,=M-+asin (149+ A)+dsin ( 4°+B)+csin (18°+C) 
(3) T,,=M+asin (21"+ A) +6 sin (18"+B) +e sin (15"+C) 
and if the epochs H,, H,, of maximum and minimum together 
with the corresponding temperatures m,, m,, were known, We 
should have the four additional equations 
(4) 0=a cos (H, + A) +26 cos (2H, + B) + 8c cos (3H, +0) 
(5) 0=a cos (H,+ A) + 26 cos (2H, + B) +3e cos (3H,+C) 
(6) m,—M=asin (H,+A)+ 4sin (2H,+B)+ esin (3H,+C) 
(7) m,—M=asin (H,+A)+ dsin (2H,+B)+ esin (3H, +C) 
