XIV. Method of determining the Latitude, by a Sextant or 

 Circle, with simplicity and accuracy, from Circum-meri- 

 dian Observations, taken near Noon. By Major-Gene- 

 ral Sir Thomas Brisbane, C. B. F. R. S. E. and Cor- 

 responding Member of the Institute of France. 



(Read November 20. 1820. j 



./\.S it very frequently happens that an observation may not 

 be obtained for the latitude, at the precise instant of noon, it 

 becomes a most desirable object to supply that loss by every 

 possible means. The method which I am about to detail, 

 I have long practised, and from the experience of many hun- 

 dred trials, I can recommend it, as combining much simplici- 

 ty with the greatest accuracy ; since one day's observations 

 may be equal to those derived from the chances of three weeks 

 of the ordinary course of weather in our climate. This me- 

 thod consists in merely reducing to noon these observations, 

 the same as if made when the sun's centre was on the meri- 

 dian, by the means of a very simple calculation, which I 

 shall detail, and illustrate with the observations for two days, 

 in order to shew the accuracy of the results thus obtained. 

 Having previously ascertained the time of noon, either by 

 equal altitudes, or from simple ones, in the manner I had the 



F f 2 honour 



