36 Prof. Forbes on the Application of the 



Kali-yug, appears, according to the mythology of the Indians, 

 also as a period of the creation, as the beginning of the existing 

 human race. If, conformably with the old Oriental opinion, 

 and as, according to the Hebrew original text in regard to the 

 period from Adam to Noah, 1656 years are reckoned from the 

 beginning of the Kali-yug as from the creation, then the time of 

 the great flood- would be fixed in the middle of the sixteenth 

 century before Christ, the period assigned to the Deucalion 

 flood by old chronologists ; while, by several determinations of 

 the time, a similar period between the creation and the deluge 

 seems fixed for the Ogygian flood, but in the sense in which 

 that period was employed in the Samaritan translation of the 

 Pentateuch. 



Note respecting the application of the Compressibility of Water 

 to Practical Purposes. By James D. Forbes, Esq. F. K. SS. 

 L. & E., Vice-Pres. Soc. Arts, and Professor of Natural Phi- 

 losophy in the University of Edinburgh *. 



Only two methods have been applied with much success to 

 the precise determination of pressures communicated in all di- 

 rections ; the one, by observing the volume of air inclosed in a 

 tube, as in the common manometer ; the other, by the actual 

 measurement of the height of an equi-ponderant column of fluid 

 such as mercury. Each of these methods is subject to grave 

 practical inconvenience : In the case of the manometer, from the 

 immense disproportion of the division of the scale for great varia- 

 tions of pressure, and, in the other, from the extremely cumbrous 

 and unmanageable apparatus which it requires when the pressures 

 are considerable. Both these methods were resorted to by the 

 Commission of the Institute of France, appointed to ascertain 

 the relation of the temperature and pressure of steam, the pres- 

 sure being ascertained by thj volume of air in a manometer, 

 previously graduated experimentally by comparison with the 

 pressure of a column of mercury. 



The idea of substituting a manometer constructed of water 

 instead of air, occurred to me a considerable time ago, when ap- 

 * Read to the Society of Arts on 22d April 1835, 



