80 



versed sine of the observed distance, above the versed sine 

 of the difference of observed altitudes. The figures in the 

 above-mentioned sum must be increased to five, if necessary, 

 by prefixing cyphers. Place the first figure of the sum under 

 the third figure of the excess from the right hand, the second 

 figure under the fourth figure of the excess, &c. thus invert- 

 ing the figures of the sum. The product found according to 

 the method of contracted decimal multiplication, is to be 

 subtracted from the excess. 



Example 



