Scientific Memoranda, 



325 



METEOROLOGICAL OBSERVATIONS. 

 Made at Wilmington, Delaware, by Henry Gibbons, M.D. 

 Summary for November, 1831. 



Therm. Barom. 



Average at sun-rise, 33°.23 m29.70 

 Average at mid-day, 47°.30 29.68 

 Average at 10 P.M. 37°.87 

 Monthly average, 40°.26 

 Maximum, 10th and 



11th, 61°. 

 Minimum, 30th, 20°. 

 Range, 41°. 

 Warmest day, 11th, 59°. 

 Coldest day, 30th, 26°. 



29.69 

 29.69 



30.03 

 28.73 

 1.30 



Proportion of clear weather, days 21 



Proportion of cloudy, 9 



Whole days clear, 16 



Days on which rain fell, 4 



Days on which snow fell, 4 

 Depth of rain, including melted 



snow m.3.02 



Depth of snow, 4 



Northerly winds prevailed days 21 



Easterly, 6 



Southerly, (S. to W.) 3 



Observations. — Auroras, none. Rain, less than in any month since June. 

 Temperature, seasonably cool in the forepart of the month, without any se- 

 vere frost : but the two last weeks wintry ; the thermometer falling below 

 the freezing point on 11 of the last 15 days, although previous to this period 

 it had not sunk so low as 32° during the whole autumn. On these 15 

 days, the average at sun-rise was 29°. This cold weather was extensively 

 felt. The navigation of the Potomac, from Washington to Alexandria, was 

 obstructed by ice on the last day of the month. A snow storm occurred on 

 the night of the 21st ; slight at Wilmington, but severe in the New England 

 states, and covering the ground 6 or 8 inches deep a few miles West of Bal- 

 timore. There were three small snows besides this. Barometer unusually 

 low in its range. On the evening of the 21st, previous to the snow-storm 

 above noticed, it sunk to 28.73 inches, a depression which it had not before 

 experienced since the destructive easterly storm of " Easter Sunday," in 

 MarcTi 1822. Winds, high and pretty constant. Clouds, very changeable 

 in form ; electrified once. Three slight easterly storms, in two of which the 

 wind soon changed to south. 



SCIENTIFIC MEMORANDA. 



Account of a new Mode of Propelling Vessels. — A paper by Mr. 

 Wm. Hall, was read before the Royal Society on this subject. 

 The author ascribes the want of success, which has hitherto at- 

 tended all attempts to propel vessels by a discharge of water 

 from the stern, to the injudicious plan of the apparatus employed, 

 and not to any defect in the principle itself, for he considers that 

 the re-action upon the vessel from which a volume of water is 

 thrown, depends in no degree on the resistance it meets with 

 from the medium into which it is ejected, but simply upon the 

 momentum given to the mass. The author proposes to accom- 



