78 General Walker — Error in Spiril-'leoeUing operations. [April, 



exhibited sLows that it was printed in the Hung Woo period of the Ta Ming 

 dynasty (A. D. 1368) so that it is about five hundred years old. 



Col. Yule was under a misapprehension in thinking Sir Harry Parkes 

 was one of those who possessed a copy of these rare notes. Sir Thomas 

 Wade the present British Minister in Peking, on being shown this note, 

 also said it was the only one of the Ming dynasty he had ever seen. 



In reply to questions asked by some of the members, Sir Pope 

 Hennessy explained that the note was " valued for one thousand," that is, 

 1000 cash, or one dollar. It bore the seals of the revenue officials, and 

 appeared to be of Imperial currency as distinguished from the local or 

 provincial paper money now used in some parts of China. The inscription 

 on it denoted that any one convicted of forging the note would be 

 punished by decapitation and any informer would receive a reward. This 

 copy was got from the Chinese a few years ago by a European official of 

 the Customs service who was well known as a collector of Chinese coins and 

 old books, and on whose death in 1878 it was sold in Hongkong. His 

 collection of Chinese coins 'was purchased by the Japanese Government. 

 The note appeared to be printed from a block. The seals, of which a 

 slight Vermillion impression was visible, were similar to those now in use 

 on official documents. 



The following papers were read : — 

 1. The Spirit' Levelling Operations executed in connection tvith the Tidal 



Ohservations of the Indian Survey Department. — By Lieut.-Geneeal 



J. T. Walkee, C. B., F. R. S., Surveyor- General of India. 



The tidal stations at Madras and Bombay have now been connected 

 by a line of spirit-levels carried directly across the peninsula, for the most 

 part in the vicinity of the line of railway. The mean-sea level has been 

 determined very approximately at each of the two tidal stations, and it 

 would appear from the spirit-levelling operations that the mean -sea level is 

 about 3 feet higher at Madras than at Bombay. That there are variations 

 in the general level of the surface of the ocean at different places, so that, 

 if compared with the surface of the spheroid or other geometrical figure 

 which most closely corresponds to the figure of the earth, the surface of 

 the ocean will in some places be above and in other places below that of 

 the figure, is probable enough ; and indeed this must certainly happen, 

 whenever the attractive influences of mountains and otlier irregularities of 

 the earth's surface on the waters of the ocean are not counteracted by 

 deficiencies of density in the strata below the elevated masses. But as tlie 

 surface of the ocean is everywhere maintained in equilibrium, there can be 

 no flow of water from one point to another ; thus there can be no sensible 

 difierences of level, though some points on the surface may be materially 



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