GEOLOGY. 279 



continued four days without intermission, varying however, in inten- 

 sity. The wind blew from the north, northeast, and northwest, fre- 

 quently shifting between these points, and varying in strength from a 

 perfect calm to a brisk breeze. The altitude of the barometer was 

 from 29.40 to 30.00 (rather lower than before and after the shower.) 

 The thermometer ranged from 36 to 81 Fahr. No rain had fallen 

 for six weeks, and the hygrometric state of the atmosphere was very 

 high. Neither cloud, fog, nor mist obscured the heavens, yet the sun 

 and moon were scarcely visible, the orb of day appeared as if viewed 

 through a smoked glass, the whole sky presenting a uniform rusty 

 hue. At times this sameness was disturbed, exhibiting between the 

 spectator and the sun the appearance of a water-spout, owing to the 

 gyratory motions of the impalpable mineral. The sand penetrated 

 the most secluded apartments ; furniture wiped in the morning would 

 be so covered with it in the afternoon, that one could write on it 

 legibly. In the streets it was annoying, entering the eyes, nostrils and 

 mouth, and grating under the teeth. My ophthalmic patients gener- 

 ally suffered a relapse, and an unusual number of new cases soon 

 after presented. Were such heavy sand storms of frequent occur- 

 rence, disease of the visual organs would prevail to a destructive 

 extent. The effect was the same when observed from the Ningpo 

 Tower, and from the summit of the low mountains in the neighborhood 

 of the city. 



The specimens I gathered fell on a newspaper placed on the roof 

 of a house. The whole quantity which fell was about ten grains to 

 the square foot. It should be remarked, however, that during the 

 four days the dust seemed suspended in the air for several hours at a 

 time, scarcely an appreciable quantity falling during these intervals. 

 The Chinese call it yellow sand ; it is an impalpable powder of that 

 color. 



It was observed at sea, at Hangchau, and at Shanghai. Whence 

 did it originate ? The opinion of the Chinese on this subject may, I 

 think, be regarded as correct. They assert that it comes from Peking. 

 We know that the sand of Sahara is sometimes elevated by whirlwinds 

 into the upper current of the air, and deposited in the Atlantic twelve 

 hundred miles, sometimes directly opposite to the trade winds. Over 

 against the vast alluvial Plain of Eastern Asia is the ocean of sand 

 the Desert of Gobi or Shamoh, extending from near the sea westerly 

 2,300 miles, and 3 to 400 broad including the conterminous sandy 

 districts. Like its counterpart in Africa, it is subject to whirlwinds 

 which raise its fine dust like the waves of the sea, and doubtless at 

 times waft it into the upper currents of air, and transport it to distant 

 regions. I have been informed by intelligent natives of Kiangsi and 

 Honan, that the phenomenon occurs in those provinces also. Assum- 

 ing the Mongolian steppes to be the source whence these showers 

 descend, the amount of sand which is annually conveyed hither must 

 be prodigious to cover such an extensive area. Regarded in a mete- 

 orological and in a geological point of view, these showers possess no 

 small interest. 



