After making a voyage or two to the Baltic, and finding that everything was working satisfactorily, the Kovno was loaded with 2,400 tons dead weight, and sailed in January, 1883, for Buenos Ayres; the Draco was loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, the distance in both cases being about 6,400 miles.  It was thought advisable, for purposes of comparison, that the ships should steam at as near as possible the same speed; and to attain this object, we considered the safest plan was to instruct the engineers as to the average amount of coal they were to burn per day, and experience with these ships on their Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 tons in the case of the Draco.  During the voyage each ship seems to have had fair average weather, and equal care was taken in getting the best results possible.  The average speed of the Draco was, however, 8.625 knots, or 207 miles per day, the engines making on the average 57.5 revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles per day, the engines making 55.5 revolutions.  The coal used was ordinary South Yorkshire, just as it comes from the pits for bunker purposes.  The indicated horse power in each case would average about 600.  The total coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a saving of 19.5 per cent. over the ordinary compounds, with an increase of speed of 6.5 per cent.

In December, 1883, one of the others, the Grodno, sailed from Bombay, and attained an average speed of 8.5 knots, or 204 miles per day, the engines making 57 revolutions, with a coal consumption of 12.8 tons per day, or 469 tons on the voyage.  The Draco’s consumption is therefore 30.5 per cent. less than that of the Grodno on the round voyage, and 20.3 percent per day.

The success of the triple compound engine was in these instances more than had been anticipated, and induced Mr. Wilson to go a step further.  The S.S.  Yeddo had been refitted with boilers made for a working pressure of 90 lb. per square inch, but owing to the size of the shafting the working pressure was limited to 70 lb.; the average consumption of coal under these circumstances on two voyages was 17 tons per day.  These boilers had a margin of safety beyond what was required by the rules when made, and as the Board of Trade rules had been modified in the mean while, it was found that they could with safety be worked at 100 lb. per square inch.  A third cylinder was now fitted on the top of the original low pressure, and the safety valves loaded to the 100 lb., and the ship was dispatched to Cronstadt.  After making two voyages under similar circumstances to the two previous ones, the average consumption was 13.5 tons per day only.  In this case it was the same ship, same boilers, same engines, same propeller, and same men, the only difference being the addition of a third cylinder and the increase of pressure.