July 15, 1870.] '^^^ [Ackerman, 



A EEGISTER of METEOROLOGICAL OBSERVATIONS made at 



BOIS CHENE, near Port-au-Priuce, Hayti. By Prop. A. Ackekman, 



National Museum. 



{Bead before tJie American PMlosopJiical Society, July 15, 1870.) 

 INTRODUCTORY REMARKS. 



All the meteorological observations have been made at "Bois Clitine," 

 S.E. from the harbor of the Capital, at an elevation of 53 meters above 

 the mean level of the sea, vs^ith the exclusion of those comprised between 

 the 19th May, 18G6, to the 17th November, 1867, which have been made 

 at "Lalue," suburb E of the Capital, country seat of General Lamothe, 

 elevation 57 meters* 



The rain-guage used is that of Babinet; its surface of reception is four 

 square-decimeters, so that a centilitre of water represents \ millimeter 

 of rain in elevation. No building, trees or other obstacles influenced 

 the quantity of received rain, and in order to avoid a correction for evap- 

 oration, the water was measured after every rain, except what fell at 

 night, which was registered before sunrise, and without having a^jplied a 

 correction. Elevation of the funnel above ground 3 feet. 



The diurnal rain comprises that which fell between 6 o clock A. M. and 

 6 o'clock P. M., and nocturnal rain that which was received in the re- 

 maining twelve hours. 



As to the division adopted for the electric phenomena of the atmos- 

 phere, the first column reproduces tlie number of days during which it 

 thundered, and lightning was perceived; however, one phenomenon may 

 have been independent of the other, for example: the thunder was heard in 

 the morning, and the lightning seen in the evening of the same day; this 

 day is noted in the first column. In order to diminish a sort of want of 

 precision in this first column, the last column represents the days of 

 "orages"f which passed above town or its near environs, notwithstanding- 

 they have already been counted in the first column. The nu.mber of days 

 during which thunder alone was heard, or lightning only perceived, form 

 the successive columns and can only be considered as minima, for the 

 j)henomena may have escaped observation, principally lightning at night. 



There are days during which thundering lasts for hours, and others 

 when lightnings are so numerous in the evenings as to amount from 30 to 

 80 in a minute of time, and so for several hours. Particulars about light- 

 nings, on colors, numbers, bifurcations, multiple divisions, distances 

 ascending and descending, &c., «&c., have been published in the Moniteur 

 Ofificiel of the Republic. 



Relative to temperature, the thermometers are standard instruments, 

 from the best makers in Paris, divided on the stem into \ centigrades, so 

 that a tenth of a degree is easily estimated; from time to time the varia- 

 tion of zero-point was verified and the correction applied to the obser- 

 vations. 



* "Lalue" and "Bois Chene" are situated about a mile from the sea shore, and both stations near 

 together, about }i part of a mile asiinder. 

 t Thunder storm and rain. 



