390 Miscellaneous Intelligence. 



rations it appears that a degree of the meridian near the equa- 

 tor contains 68.704 English miles ; that in 45° of latitude it is 

 69.03; in 51°, 69.105; in 90°, 69.368. So that a degree of 

 latitude at a medium estimate makes exactly 69.I English geo- 

 graphical miles. — Monthly Magazine. 



3. Geographical Measurements in Denmark. — During the last 

 two years geographical labours have been carried on in Den- 

 mark, under the auspices of the Kiug, for the measurement of 

 degrees from Skagen to the tower of the church of St. Michael, 

 at Strasbourg. These are intended to connect with similar 

 measurements ordered by the governments of Hanover and 

 Bavaria. On the completion of these labours it is intended 

 that the instruments used in them, which are very superior, 

 shall be conveyed to the Mediterranean to be employed in 

 similar undertakings. 



His Danish Majesty has also ordered the publication of a 

 Nautical Almanac that will contain the distances of the planets 

 from the moon. A calculator has been expressly appointed to 

 act under the directions of M. Schumacher. The first al- 

 manac will shortly appear, and will be for 1822. 



4. On the Structure of Glass when in a state of Vibration. — 

 M. Biot has ascertained that when the particles of plates of 

 glass were made to perform longitudinal vibrations, the glass 

 became altered in structure and affected polarised light. The 

 glass was about 80 inches long, 1.18 inches wide, and nearly 

 .28 of an inch thick. A ray of polarized light was made 

 to fall on a black glass plate at such an angle as to be absorbed, 

 and then the plate of glass being held in the middle, one half 

 was rubbed with a wet cloth, whilst the other was held in the 

 ray before the absorbing glass. Immediately that sound was 

 produced by the friction, the black receiving mirror shone with 

 the light it reflected, but the moment the sound ceased the 

 light ceased also. So that it was evident the glass, whilst 

 in a state of vibration, had the power of afTecting the polarized 

 light. 



