Buccaneer of the Star Seas

... and thou shalt be immortal! Such was the curse of that 13th Century sorcerer. Now Carlyle roamed the uncharted star-seas, seeking Death as he sought the richly-laden derelicts in that sargossa of long-vanished space-galleons.
An unpleasant shudder went through Thaddeus Carlyle as the great iron door thundered behind him. Reading Gaol's raw, damp atmosphere seemed to settle into his bones. Hobbling on rheumatic legs, the aged turnkey preceded him down the vaulted stone corridor.
'Tis the first time my key has disturbed Friar Bacon's lock these six months, his grumbling voice came to Carlyle's ears. Plagued few they are that visit the roguish priest. Not even the canon comes now, to exhort him to renounce his black magic.
Thaddeus Carlyle's dark eyes flamed with quick interest. Then he practices still these works of the devil? he queried softly.
The turnkey stopped, his narrowed eyes mirroring fearful thoughts. With his crooked forefinger he tapped the young nobleman's gold-cloth tabard.
Only last month he asked for brimstone, charcoal and niter. We gave him the stuff, seeing no harm. A week ago, as I am passing his cell, there was a great flash and roar. The devil's powders had exploded as steam bursts a tight-lidded vessel! He carries still the marks of a burn.
No! Carlyle's smooth features were blank. Fire—from such stuff as that?
That's not all, my Lord. Friar Bacon tells me that if we would give him enough of the stuff and a long tube, he could throw an iron ball across the Thames!
Turning away with a crafty nod and a meaningful blink, the turnkey led on to the mean little cell in which Roger Bacon had now spent nine years. The visitor was openly affected by the jailer's incredulous story. He had heard strange and terrible things of the Gray Friar. The church, in incarcerating him, had accused him of consorting with the devil. Some whispered that he had learned the secret of immortality. That was the rumor which had brought Thaddeus Carlyle, the second Lord Monfort, into the gloomy confines of Reading Gaol.