1848.] The Neutral Point of Barometers. 533 



mucus membranes, especially that which lines the air passages." The 

 writer of the Burmese medical treatise recommends the exude of the 

 tree for the usual purposes to which the Balsam of Peru is applied, 

 under the delusion that it is the same substance ! 



Here is a fine illustration of the fallacies of medicine. It is proba- 

 ble that this substance has been used in all the various cases many 

 times by the author, and quite as much good done, and as wonderful 

 cures effected, as if he had used the veritable Balsam of Peru. And 

 the same glorious effects are still being produced, for the book is in the 

 hands of many natives and is highly valued, but no part more so than 

 this, because it points them to a production of the country, while most 

 of the medicines mentioned are foreign productions. 



It seems to me that our liquid storax might be made an article of 

 commerce, but I know not how it sells in the market. 



The tree is called by the Burmans sSoOCjOO Nan-ta-rouk. 



Note on a method of determining the Neutral Point of Barometers 

 having small circular cisterns. — By Capt. J. C. Hannyngton, 

 24th B. N. I. Assistant Commissioner, Chota Nagpore. 



1 . For any barometer having a circular cistern of small diameter, let 

 h be the approximate height of the column of mercury, - the ratio 

 of the capacities of the tube and cistern, P the neutral point, and H 

 the true height, then, 



2. When two or more barometers are compared together side by 

 side, the vacuum in each being equally perfect, it is for practical pur- 

 poses assumed that after applying the small corrections for capillary 

 repulsion, and difference of temperature, the actual heights of the 

 several columns are equal. 



3. Therefore if P, the neutral point of the instrument from which 

 h is derived, and of which - is the ratio of the capacities, be un- 

 known ; H may be obtained by simultaneous observations with another 

 barometer, and this independent value of II may be put in the above 

 equation, which will still remain true. 



4 c 2 



