100 



REPORT 1842. 



Table (Continued). 



The difference of each two consecutive numbers taken from the counter 

 shows the number of strokes made by the engine between the correspond- 

 ing observations, and the difference of each two consecutive numbers taken 

 from the indicator shows the number registered by the indicator whilst this 

 number of strokes is made by the engine. These differences are given in 

 the third and fourth columns of the table. 



The number registered by the indicator whilst any number of strokes is 

 made by the engine, being divided by that number of strokes, gives the mean 

 registration of the indicator per stroke of the engine, between the periods of 

 observation. The quotients obtained from this division, in respect to all the 

 observations, are shown in the last column of the table. 



Between the 28th of January and the 18th of February the engine made 

 179777 strokes, and the indicator registered the number 133955*6, being a 

 mean registration of -7451 per stroke of the engine. 



Between the 28th of January and the 25th of February (being the whole 

 time of the working of the indicator) the engine made 232617 strokes, and 

 the indicator registered the number 173 176*7, being a mean registration of 

 '7444 per stroke of the engine. 



Now the general formula for determining the work of the engine from the 

 number registered by the indicator, as demonstrated in the report made by 



* On the 18th the cord got out of the pulley of the indicator, and it is not known how 

 much was lost in the registration before the accident was discovered and the cord replace d ; 

 supposing, however, that throughout the 4603 strokes made by the engine between the two 

 observations on the 18th, the registration had continued the same, -746 per stroke, as between 

 the two preceding observations, the number registered would have been 3 433'8, which added 

 to the previous registration, gives 137818 - 9 for the number which would have been shown by 

 the indicator; the number actually shown was 137280-2 : so that on this supposition the 

 number lost by the indicator, whilst the cord was out of the pulley, was 538-/. This num- 

 ber is added as a correction to all the registrations of the indicator after the 18th. The num- 

 bers in the last column can only be affected by any error in it on the 18th and 19th ; any such 

 error must be inconsiderable. 



