[ 51 ] 



V. A simple Rule for co?ivertitig intervals of Sidereal into 

 intervals of Mean Solar Tirne^ and vice versa, isoithout the 

 help of Tables. By the Rev. J. M. Heath*. 



I. "^"^TRITE down the given time. 



▼ ▼ II. Underneath its minutes, seconds, and decimals 

 of second, write its hours, minutes, and decimals of minute, 

 respectively, retaining three decimal places. 



III. Subtract II. from I. 



IV. Subtract II. from III., retaining the first decimals of 

 hours only. 



V. Write the liours, minutes, and decimals of minute in III. 

 as minutes, seconds, and decimals of second respectively. 



VI. Divide V. by VI., and place ihefrst decimal of hour 

 in IV. under the third decimal place of the quotient, writing 

 the integral number of hours to the left, and add. 



VII. To I. add its third part, and the hundredth part of 

 their sum, retaining only the first decimal place of the hours. 



VIII. As in VI., place the decimal of hour of VII. under 

 the tliird decimal of second in I., writing the entire hours to 

 the left, and add. 



Then, the sum or difference of VIII. and VI. gives the si- 

 dereal, or the mean solar time, of which I. is solar or the 

 sidereal time respectively, accurately to the third decimal of 

 seconds. h m s 



Example. I. 17 15 4.7-2'l. 



II. 17 15-787 



= 16 '^•7 nearly. 



2 49-921 



VII. 17 15 



47-24 



17- 



5- 





 25 

 75 

 22 



I. 



of I. 



1 

 j^-Q of sum. 



VIII. 17 



Then adding or sub 

 tracting VI. 



Sidereal time for I. . = 

 Mean solar time for I. = 



} 



15 



2 



47-472 

 49-921 



17 

 17 



12 



37-393 

 57-551 

 Communicated by the Author. 

 E2 



