The travel times mentioned, about a month from Earth to Neptune, give average acceleration/deceleration of about 0.25g, though if I'm reading it right ships start very slowly and decelerate faster than they accelerate. From Neptune onwards acceleration must be a lot faster, since it's only a few months to Sirius. Since this a universe that has Æther and several other mysterious forces it shouldn't be too hard to find a way to justify it.
Meanwhile, I have names for some mysterious forces - can anyone suggest derivations, or a theory of circa 1900 they might have fitted:
The nature of the attraction of gravitation, and of the ether which was supposed to pervade all space, was found out, as well as the constitution of matter, and the nature of cohesion and of the force which was known to the scientists of the nineteenth century as electricity.
The nature of these forces being known, numerous properties belonging to them that had been previously unknown were deduced, and found to be of considerable practical importance. The most wonderful of all was the discovery that the attraction of gravitation could be prevented from acting on a body by surrounding it with wires, through which peculiarly constituted currents of electricity were flowing, or, in other words, it was possible to take away a body's weight altogether. The result was that flying machines were made practicable, and these soon became almost the sole means of locomotion. Ordinary vehicles could also have their weights reduced to nothing, and consequently required less force to propel them. About the same time a new light was discovered, which was so powerful and so easy to produce that it immediately superseded the old electric light.
Great as these discoveries were, still more astonishing ones were in store. The ether-motions were still further investigated, and the result was that three new and extremely powerful forces were discovered. These were Dynogen, Pralion, and Ednogen, and practically illimitable supplies of them could be obtained from the regions of space. They could be used either separately or in combination, according to the nature of the effect desired. When all three were set in action together, an amount of energy equal to many thousands of horse-power could be obtained from an engine of very small compass. It was then that the crowning application of all these discoveries was made, and this was the navigation of space. Gravity could be annihilated at will, and there was an enormous force at the disposal of the engineers, so cigar-shaped vessels were made perfectly air-tight, and fitted with engines for acting on the ether of space, and with the anti-gravitation apparatus. After several failures, successful trips were performed to the moon and the nearer planets. The interstellar ships were gradually improved, and an ingenious steering apparatus was added, together with instruments that registered the speed of the vessel, its distance from its destination, and the existence and exact position of any obstacles that might be in the way.
So... any thoughts on Dynogen, Pralion, or Ednogen?