Meteorological Observations. 479 



The value of the dip is the mean of the three following amounts, 

 68022',25, 68o22',67, and 6So22',25, obtained in succession on the 

 31st of March. These observations were made under very favourable 

 circumstances. As in preceding years, it was thought proper tc 

 make the different observations for the declination and the dip at 

 the same time of year and about the same hours of the day. 



NOTE ON THE UNDULATORY THEORY OF LIGHT. 

 BY JOHN TOVEY, ESQ. 

 To the Editors of the Philosophical Magazine. 

 Gentlemen, 

 I perceive that the formulae (18) of my paper in your present vol., 

 p. 171, appear to lead to contradictory results; I shall be glad, 

 therefore, if you will allow me to say, that this matter will be cleared 

 up in my next paper, which will contain an improved method of find- 

 ing the general integrals. 



I am, Gentlemen, yours, &c., 



John Tovet. 

 Littlemoor, Clitheroe, May 13th, 1839. 



METEOROLOGICAL OBSERVATIONS FOR APRIL, 1839. 



Chiswick. ~. A-piW 1. Rain. 2. Overcast. S, 4. Bleak and cold. 5. Snow- 

 ing. 6. Cloudy and cold. 7. Fine. 8. Snowing. 9. Bleak and cold. 10, 

 11. Fine but cold. 12—14. Cloudy and cold. 15. Overcast. 16. Very fine. 

 17. Showery. 18. Boisterous with rain. 19. Very fine. 20. Showery. 21. 

 Fine. 22. Very fine. 23. Rain. 24 — 26. Fine. 27. Dry haze. 28 — SO. 

 Very fine. 



Boston. — April 1. Fine. 2. Stormy. 3 — 7. Cloudy. 8. Cloudy : sleet early 

 A.M. 9. Cloudy. 10. Fine. 11—15. Cloudy. 16. Fine. 17, 18. Rain. 

 19. Fine: rain early a.m. 20,21. Fine: rain a.m. and p.m. 22. Fine: rain 

 early a.m. 23. Rain. 24—26. Cloudy. 27. Cloudy : rain a.m. 28—30. Fine. 



Applegarlh Matise, Dumfries-shire. — April 1. A most inclement day : snow on 

 hills. 2. The same: snow on hills melting. 3. The same: bitterly cold. 4. 

 Another piercing day : cloudy p.m. 5. Still extremely cold : snow showers. 6. 

 Wind fallen : more temperate. 7. Moderate day : still no vegetation. 8. Pier- 

 cingly cold and withering. 9. Dry and cold: frosty mornings. 10. Sun warm, 

 but wind cold and withering. 11. Milder, but still no spring. 12. Great in- 

 crease of temperature. 13. Sun warm : wind moderate but parching. 14. Mo- 

 derate day : vegetation commencing. 1 5. The same : temperature lower : 

 cloudy. 16. Threatening rain : showery: very wet p.m. 17. .Showers: rain: 

 hail: cleared p.ji. 18. Frequent showers : rain and sleet : snow. 19. Violent 

 wind: showers of hail. 20. Dry and cold : vegetation at a stand. 21. Dry: 

 temperature rising. 22. Foggy morning : drizzling day. 23. Clear : tempera- 

 ture increasing. 24. The same : cool evening. 25. Temperature increasing : 

 clear sun. 26. Cloudy: threatening, cleared up p.m. 27. Clear and fine : 

 hoar frost morning. 28. The same : cloudy p. m- 29. Fine spring day. 30. 

 Remarkably fine spring day. 



Sun 25 days. Rain 4 days. Snow 2 days. Hail 2 diiys. Frost 3 mornings. 



Wind easterly 13 days. Southerly 12 days. Northerly 2 days. Westerly 3 

 days. 



Calm 1 1 days. Moderate 7 days. .Strong breeze 4 days. Stonny 5 days. 

 Brisk 3 days. 



Mean daily range of barometer 0'092. Mean nightly range O'OSO. Mean 

 range of 24 hours 0*172. 



Mean daily range of thermometer 10"4. 



