Meteorological Observations. 507 



if the metallic plate sometimes offers a slight advantage in regard to 

 rapidity, it loses it completely when inversion of the images would 

 be inadmissible, and apparatus for reversing it is required. — Comptes 

 Rendus, Sept. 15, 1851. 



REFLEXION OF LIGHT FROM THE SURFACE OF LIQUIDS. 



The following are the conclusions' of M. Jamin, from a series of 

 experiments recorded in the Annates de Chimie et de Physique for 

 February 1851 : — 



1st. Liquid surfaces polarize light incompletely and elliptically. 



2nd. Liquids having a high index of refraction have a positive 

 anomaly, or difference of phase, between the principal components 

 of the reflected motion. 



3rd. This anomaly becomes negative when the index is very small. 



4th. There are substances, whose indices are about 1*4, whose 

 polarization is rectilineal. 



5th. The laws of the intensities and anomalies are represented by 

 the formulae of M. Cauchy. 



6th. If substances are superposed, the reflexion from their surface 

 of separation follows the same laws. 



7th. In this case it is impossible to predict the value and the sign 

 of the coefficient of ellipticity. 



The memoir moreover includes a table of the constants of reflexion 

 for a number of liquids. — Journal of the Franklin Institute, July 1851 . 



METEOROLOGICAL OBSERVATIONS FOR OCT. 1851. 

 Chiswick. — October 1. Densely clouded : rain. 2. Overcast: showery. 3. Fine: 

 showery. 4. Rain : very fine : clear. 5. Fine. 6. Rain early : very fine. 7. 

 Rain. 8. Very fine. 9. Foggy: drizzly: rain. 10. Cloudy. 11. Foggy: 

 very fine. 12. Cloudy. 13. Very fine: rain. 14. Very fine. 15. Constant 

 rain. 16,17. Clear : very fine. 18. Fine: rain: cloudy. 19. Fine : overcast. 

 20. Slight drizzle : uniformly overcast. 21. Foggy : fine. 22. Slight fog : hazy. 

 23, 24, 25. Overcast. 26. Fine. 27. Overcast : exceedingly fine. 28. Over- 

 cast : rain. 29. Fine : clear. 30. Clear : fine. 31. Very fine. 



Mean temperature of the month i 51°*25 



Mean temperature of Oct. 1850 44 -32 



Mean temperature of Oct. for the last twenty-five years . 50 '50 



Average amount of rain in Oct 2*66 inches. 



Boston. — Oct. 1. Fine: rain p.m. 2. Fine. 3. Rain: rain a.m. and p.m. 

 4. Cloudy: rain a.m. 5. Fine: rain a.m. and p.m. 6. Fine: rain early a.m. 

 7,8. Fine. 9. Cloudy : rain a.m. and p.m. 10,11. Fine. 12. Cloudy. 13. 

 Cloudy: rain p.m. 14. Fine. 15. Cloudy: rain early a.m. and p.m. 16 — 

 19. Fine. 20. Cloudy. 21. Rain. 22. Fine. 23— 25. Cloudy. 26, 27. Fine. 

 28. Cloudy: rain p.m. 29. Fine: rain p.m. 30. Cloudy : rain a.m. and p.m. 

 31. Fine: rain p.m. 



Sandwick Manse^ Orkney. — Oct. 1. Bright: clear: aurora. 2. Rain : clear : 

 aurora. 3. Bright: clear. 4. Rain: clear: large lunar halo. 5. Bright: 

 showers. 6. Cloudy : showers. 7. Cloudy : rain. 8. Bright : lunar rainbow. 

 9. Bright: showers. 10. Showers : cloudy. 1 1 . Clear : showers. 12. Cloudy: 

 damp. 13. Cloudy: showers. 14. Bright: showers. 15. Rain: bright: 

 showers. 16. Bright : clear. 17. Showers : drops. 18. Showers : rain: aurora. 

 19. Clear : showers : aurora. 20. Bright: cloudy: rain. 21. Bright: cloudy. 

 22. Bright : clear : aurora, 23. Damp ; drops : aurora. 24. Fog : fine. 25. 

 Fog : rain. 26. Drizzle: rain. 27. Fine : cloudy : rain. 28. Rain : showers : 

 aurora. 29. Sleet-showers: aurora. 30. Cloudy. 31. Rain : showers : aurora. 



