LoppEr.—On Compound Engines. 147 
The Tables on page 146 will show at once the comparative results of the 
two systems in point of economy and speed. Tables A and B are an extract 
from the ships’ log by the chief officer; they show in the first place the average 
number of hours on the passage each way. 
It will be well to notice a coincidence between Tables A and B in point of 
time on the down trips. Table A gives an average with the compound 
engines of 56 hours for the down trips from Auckland to N: apier, and 64:17 
hours for the up trips from Napier to Auckland—thus making the down trips 
in twelve per cent. less time than the up trips. 
In working out the averages in Table B, very nearly the same result 
occurs. The down trips made with the old engines took 56:5 hours, and the 
up trips 64:7, being twelve per cent. quicker on the down trips, the same as 
with the compound engines. The result gives for Table A one per cent. in 
favour of the compound engines in point of speed, taking the average of five 
months’ running. 
Table C shows the consumption of coals with the compound engines for 
the voyage per hour. Table D shows the same for the old engines. 
On comparing C and D we find a saving in fuel of 42-1 per cent. with 
the compound engines, and this, with the increase of one per cent. in speed, 
requires for its attainment three per cent. more power. 
This consumption does not include the coals used for banked fires, cooking 
purposes, or steam winch. I have made the same deductions for Table D as 
for Table C for these purposes. 
With regard to the general working of these engines up to the present 
time there is every reason to be satisfied. Certainly there has been one 
source of annoyance, and that has been the excessive priming, actually in 
some instances taking the water right through the engines into the surface 
condenser ; but since the addition of another steam dome on the boiler, 
connecting it with the superheater, the excessive priming has ceased, but the 
water still rises in the gauge-glass several inches above its true level. I find 
from i inquiries that this is the case, more or less, in all boats using surface 
condensers, even with low-pressure steam. 
Before going into the various questions that arise with reference to priming, 
the chemical and electric actions of the steam and water on the boiler, T shall 
endeavour to show by comparison, theoretically, the superiority of the com- 
pound principle. I have stated my belief that nearly every screw-steamer on 
the coast of New Zealand could be similarly converted, and with equally good 
results. Supposing we take two examples with a similar class of engines, to 
those in the “Star of the South,” but much larger—say one of the steamers 
now plying on the coast (s.s. “ Pheebe”), of which I have been furnished- with 
dimensions of engines, consumption, etc. We have to find from the data 
