278 Mr. Trimmer on the [Oct. 



readily turned towards the sun. At the distance of the focal 

 length was placed a vertical circle of pasteboard moving on an 

 axis, and divided into white, grey, and black compartments. 

 Soon after the commencement of the eclipse, the lens was 

 exposed to the smi's rays, and from a mean of several trials, the 

 white part of the pasteboard was burned through in 11 seconds; 

 at the time of the greatest obscuration, the sun's rays were so 

 much weakened, that no effect was produced on either the white, 

 grey, or black paper. On the termination of the eclipse, the 

 white was perforated in 24 seconds; the difference between the 

 first and third experiments is partly to be attributed to the 

 decrease of the sun's altitude, and partly to the interposition of a 

 thin cloud. Clouds prevented Venus being seen at this place. 

 No dew was perceptible during the eclipse ; and the diminution 

 of light was not so great as expected, it far exceeding the bright- 

 est moonlight. 



The telescope used was a five feet acromatic made by DoUand, 

 and the magnifying power 80. 



Article VI. 



On the Climate of Neiv South Wales. By Mr. Trimmer. 



(To Dr. Thomson.) 



DEAR SIR, Brentford, Aug. 12, 1820. 



The New South Wales Almanack for 1820 having lately come 

 into my hands, I have extracted from it an account of the usual 

 state of the weather at Sydney, thinking that, perhaps, you 

 might deem it sufficiently interesting to insert it in the Annals of 

 Philosophy. I am, dear Sir, your obhged humble servant, 



James Trimmer. 



Jan. 

 1. Frequent vivid hghtning. 

 4. Dry squalls, creating clouds of dust. 

 10. Heat frequently intense, and but for nocturnal dews the 



fields and gardens would be literally scorched up. 

 17. The harvestmg is mostly over. 



Thermometer exceeds 62° at sunrise, and at noon up to 80% 

 90°, and sometimes 100°, and upwards. 



Feb. 



1. Mornings and evenings very agreeable. 



6. Light showers to be expected. 

 10. Days continue warm, and sometimes sultry ; lightning not 

 unfrequent. 



