44 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



RAINFALL. 



In order to measure approximately the rainfall a gauge was impi'ovised with the aid of a tin 

 can of uniform diameter. The frequent showers gave in general an inajjpreciable amount of rain, 

 though some of them gave small amounts, one-tenth of an inch or over. The meteorological 

 summary gives the record of the rainfall, from which it will be seen that the total amount during 

 the two weeks was about 8 inches. More than half of this fell in the rain-storm of May 4, when 

 it rained hard and steadily from midnight to 9.50 a. m. 



WIND. 



The observations of the direction and velocity of the wind give some interesting results. The 

 former was almost always noted as east or northeast, and was at no time observed to be from any 

 other quarter than between north and east. The island is situated in the region of the southeast 

 trades, which makes it noteworthy that not a single record gives a direction south of east. 



The table of wind velocities on page — gives in detail the results of the anemometrical obser- 

 vations. From this it will be seen that there is no indication sufficiently marked of any diurnal 

 change in the wind's velocity. It is, however, apparent that there was a decrease of velocity from 

 the beginning of the series to May 2, and an increase to May 7. These dates follow the dates of 

 mininnim and maximum pressure mentioned above by an interval of about two dajs, but the series 

 is for too short a period of time to warrant the drawing of any inferences as to their relation. 

 Indeed, it may be said that the indications of periodicity in both these cases may be only acci- 

 dental, and not real indications of a progressive movement. It would take a longer continued series 

 of observations to decide the question, and therefore the above are in Mitioned as only possibilities 

 which these observations suggest. 



The average hourly velocity of the wind was G.05 miles ; the largest total movement in twenty- 

 four hours was 212.3 miles, from 7 a. m. May 7 to 7 a. m. May 8 ; the least 59.2, between the same 

 hours May 4 and 5. The highest velocity observed was on April 30, during the passage of a 

 squall which was characterized by wind without rain. At 12.35 p. m. the anemometer registered 

 1 mile in 3'" 40", the equivaleut of 10 miles an hour. The wind usually increased during the pas- 

 sage of the heavier showers. 



METEOROLOGICAL OBSERVATIONS BETWEEN APRIL 25 AND MAY % 1883. 



The observations given below were made with the following instruments: 



Aneroid barometer, Hottinger, 3241. 



Dry-bulb thermometer. Green, 799, stem graduated. 



Wet-bulb thermometer. Green, 797, stem graduated. 



Maximum thermometer, Green, 725, stem graduated. 



Minimum thermometer, Green, 710, stem graduated. 



Minimum thermometer for use at ground. Hicks, 5521, stem graduated. 



Robinson's anemometer. Green, 111. 



Tlie readings of these instruments are given exactly as recorded, with the following exceptions : 



The readings of the maximum thermometer have been corrected by the amount — 0°.5, deter- 

 mined by thirty-seven comparisons with the dry bulb made April 27-30. 



The readings of the minimum thermometer. Green, 710, have been corrected by the value. 

 -f 0O.4, determined by sixty-two similar comparisons; those of the minimum thermometer. Hicks, 

 5.521, by + 2O.0, determined by forty similar comparisons. The large correction to the latter was 

 due to a bubble in the instrument, which was several times removed, but as often formed again. 



