Meteorological Observations. 899 



after having been made, as the iron becomes peroxidized and spoilt 

 by a prolonged contact with the collodion. 



The nitrate of silver solution for exciting the plate should be of 

 the strength of 30 grs. to the ounce of water. 



The developing solution may be either the ordinary sulphate of 

 iron, or the pyrogallic acid. 



With a good lens and a good light an almost instantaneous picture 

 may be produced by this process. 



A little water of ammonia added to the hyposulphite bath brings 

 out the picture more fully when a very short exposure is given. 



Sometimes the common table salt contains a little carbonate of 

 soda ; if such be used in the process, it causes cloudiness. — From the 

 Journal of the Photographic Society, April 21, 1855. 



METEOROLOGICAL OBSERVATIONS FOR MARCH 1855. 



Chiswick. — March 1. Heavy rain: very fine: halo round the moon in the 

 evening. 2. Cloudy : rain. 3. Low white clouds : heavy rain : clear and fine. 

 4. Clear : cloudy and fine. 5. Slight fog: very fine. 6. Cloudy and fine : foggy. 

 7. Frosty : fine. 8. Very clear : fine : sharp frost. 9. Frosty : few snow-flakes : 

 overcast. 10. Snowing: sharp frost at night. 11. Cloudy: rain at night. 12. 

 Cloudy: rain. 13. Fine. 14. Fine: cloudy. 15. Cloudy: rain. 16. Densely 

 overcast : fine. 17. Fine : rain : clear. 18. Cloudy and boisterous. 19. Showery. 

 20. Foggy : very fine. 21. Cloudy and cold : hail-shower. 22. Sleet : cold rain : 

 overcast : boisterous. 23, 24. Cloudy and cold. 25. Fine : sharp frost at night. 

 26. Clear : cloudy : fine. 27. Very fine. 28. Drizzly : heavy rain. 29. Cloudy : 

 clear and fine. 30. Cloudy. 31. Heavy clouds : clear and fine. 



Mean temperature of the month 37°"61 



Mean temperature of March 1854 42 "54 



Mean temperature of March for the last twenty-nine years... 42 *24 



Average amount of rain in March 1-33 inch. 



Boston. — March 1. Fine: rain p.m. 2. Fine. 3. Fine: stormy and rain a.m. 



4, 5. Fine. 6, 7. Foggy. 8. Fine. 9. Cloudy. 10. Fine. 11. Fine : snow r.M. 

 12. Cloudy : rain p.m. 13. Rain : rain a.m. 14. Cloudy. 15. Fine. 16. Fine: 

 rain a.m. 17. Cloudy : rain a.m. and p.m. 18, 19. Fine. 20, 21. Cloudy. 22. 

 Cloudy : snow a.m. 23— 25. Cloudy. 26. Fine. 27, 28. Cloudy. 29— 31. Fine. 



Sandwick Manse, Orkney. — March 1. Showers a.m. and p.m. 2. Rain a.m. and 

 p.m. 3. Rain a.m. : drizzle p.m. 4. Clear a.m. : cloudy, large solar halo p.m. 



5. Clear a.m. : cloudy p.m. 6. Bright a.m. : clear, fine p.m. 7, 8. Bright, hoar- 

 frost a.m. : clear, frost p.m. 9. Bright, hoar-frost a.m. : clear, drops p.m. 10. 

 Snow-showers a.m. : cloudy p.m. 11. Cloudy a.m. : snow-showers p.m. 12. Snow- 

 showers a.m.: snow-drift r.M. 13. Snow a.m. : cloudy p.m. 14. Bright a.m. : 

 clear, aurora p.m. 15. Bright a.m. : cloudy p.m. 16. Rain a.m. : cloudy p.m. 

 17. Clear a.m. : damp p.m. 18. Rain a.m. : showers, aurora p.m. 19. Bright a.m. : 

 clear, aurora p.m. 20. Bright a.m. : clear p.m. 21. Clear a.m. : clear, aurora p.m. 

 22 — 24. Snow-showers a.m. : clear p.m. 25. Snow-showers a.m. and p.m. 26. 

 Snow a.m. : clear, frost p.m. 27. Snow, clear a.m. : cloudy p.m. 28. Cloudy 

 a.m.: clear p.m. 29,30. Clear a.m. and p.m. 31. Bright a.m. : clear p.m. 



Mean temperature of March for twenty-eight previous years... 40°-53 



Mean temperature of this month 36 - 61 



Mean temperature of March 1854 45 -14 



Average quantity of rain in March for fourteen previous years 252 inches. 



The mean temperature of this month is lower than that of March during any 



of the twenty-eight years of my observations, except in 1837, when it was 36°-54, 



and in 1839, when it was 36°33. That of March last year was the highest during 



the whole period. 



