Time of Sunrise and Sunset at Singapore and 

 Penang throughout the Year. 



By It. Marriott. 



Accompanying this note is a chart showing the times of sunrise 

 and sunset at Singapore and Penang throughout the year. 



Each space on the chart represents horizontally an interval of 

 five days and vertically one minute. 



A dotted curve shows the * equation of time ' (i.e. the difference 

 between apparent solar time as indicated by a sun-dial and mean- 

 time as recorded by the clock). Bearing in mind that by using 

 the standard time of the 105th degree of longitude instead of that 

 of our own longitude of 103° 50', our clocks in Singapore are 4 

 minutes 40 seconds ahead of the true time, this dotted line shows 

 how very small is the variation due to our small northern latitude. 

 In Penang the corresponding amount of ' daylight saving ' is 18 

 minutes 36 seconds, but in addition there is quite an appreciable 

 variation on account of latitude. In Singapore the difference be- 

 tween the lengths of the longest and shortest days in the year is 

 onlyubout 9 minutes, in Penang the difference is 36-| minutes. At 

 both places there are two maxima and two minima in the curves, 

 but while in Singapore the longest evenings are in February and 

 are entirely caused by the ' equation of time/ in Penang the effect 

 of latitude is sufficient to make the evenings longer in July than 

 in February. 



The times calculated are the Singapore standard times at which 

 the centre of the sun's disc is visible on the horizon to an observer 

 at the sea level, allowance being made for the fact that owing to 

 refraction the sun is visible when in reality it is 36' below the 

 horizon. 



taur. Straits Branch R. A. Soc, Ko. 70. 



