431; Notes and Memoranda. 



impossible to tell from Dr. Ozanam's description what proportion of carbonic acid 

 his patient really did inhale. Professor Miller says, " if the proportion exceeds 

 three or four per cent, of the air, it acts as a narcotic poison." We mention this 

 as a warning to our non-medical readers against foolish experiments. 



Mountain Barometer. — Under tbis title Messrs. Home and Thornthwaite 

 have produced a very excellent aneroid, especially adapted to facilitate the measure- 

 ment of heights. Being only 2\ inches in diameter, it is very portable, wbile from 

 the excellent workmanship, no practical loss of efficiency is the consequence of its 

 reduced size. The face is graduated in two circles, the outer one giving the baro- 

 metrical pressure in inches and tenths of an inch. Below this is the second circle 

 upon winch the peculiar convenience of the instrument depends. This is graduated 

 in spaces corresponding with hundreds and thousands of feet, so that a mere 

 inspection is sufficient, without any calculation, for the measurement of ordinary 

 heights. Thus if the hand , points to 1000, and on being carried to an elevation 

 indicates 1100, it is evident that the last station is 100 feet higher than the first. 

 Where the elevation to be measured is considerable, there will be a difference of 

 temperature between the upper and lower levels, which must be allowed for to 

 obtain a correct result ; and the makers of this instrument supply a convenient 

 and easily worked table, calculated in degrees of Fahrenheit according to the 

 formula of La Place. To test the accuracy of the instrument, we have made 

 repeated trials with heights of twenty or thirty feet and upwards, always obtaining 

 closely approximate results. We have also compared its indications with a mercurial 

 barometer, and observed its prompt indications of slight changes in the density 

 of the air. We have likewise carried it loose in our pockets during long walks, 

 and on two railway journeys, to see if a good shaking would do it any harm. The 

 result of these experiments has been very satisfactory, and we can, therefore, 

 recommend it to the tourist as a pleasant companion, serving the double purpose 

 of a good barometer and measurer of heights. 



New Planet.— Mr. Tuttle, Cambridge, IT. S., has discovered the 73rd planet. 

 The asteroid resembles a 13 magnitude star, and was seen on the 8th of April, 

 near £ Virginis. 



Soap Bubbles and Meteorology. — M. Felix Plateau having been requested 

 by his father to throw away a liquid of a bad quality which had been employed 

 to produce films, endeavoured to make it form a sheet of liquid in its descent, 

 when to his surprise it took on the shape of a large bubble, and fell slowly. He 

 repeated the experiment a good many times with soapsuds, and sometimes suc- 

 ceeded in making as many as fifteen bubbles at a time. He recommends a hemi- 

 spherical vessel about five inches diameter, holding a considerable quautity of the 

 fluid, which should be thrown at an angle of 45° with the horizon, and have a 

 spinning motion communicated to it. In this experiment the elder Plateau saw 

 an illustration of the formation of vesicles of vapour. The Abbe Moigno remarks 

 in Cosmos that such a result was quite unexpected, and is eminently curious. 





