Both were men of means， with little inclination and nonecessity for professional life. My friendship and theirmutual animosity were the two things that linked them inany way together. While they were very often at my place，they made it a fastidious point to avoid each other on suchvisits， though it was inevitable， under the circumstances，that they should come upon each other occasionally.
On the day I have in recollection， Paul Tichlorne hadbeen mooning all morning in my study over a currentscientific review. This left me free to my own affairs， andI was out among my roses when Lloyd Inwood arrived.
Clipping and pruning and tacking the climbers on theporch， with my mouth full of nails， and Lloyd followingme about and lending a hand now and again， we fell todiscussing the mythical race of invisible people， thatstrange and vagrant people the traditions of which havecome down to us. Lloyd warmed to the talk in his nervous，jerky fashion， and was soon interrogating the physicalproperties and possibilities of invisibility. A perfectly blackobject， he contended， would elude and defy the acutest vision.
“Color is a sensation，” he was saying. “It has no objectivereality. Without light， we can see neither colors norobjects themselves. All objects are black in the dark， andin the dark it is impossible to see them. If no light strikesupon them， then no light is flung back from them to theeye， and so we have no vision-evidence of their being.”
“But we see black objects in daylight，” I objected.
“Very true，” he went on warmly. “And that is becausethey are not perfectly black. Were they perfectly black，absolutely black， as it were， we could not see them—ay， notin the blaze of a thousand suns could we see them！ Andso I say， with the right pigments， properly compounded，an absolutely black paint could be produced which wouldrender invisible whatever it was applied to.”
“It would be a remarkable discovery，” I said noncommittally，for the whole thing seemed too fantastic for
aught but speculative purposes.
“Remarkable！” Lloyd slapped me on the shoulder. “Ishould say so. Why， old chap， to coat myself with such apaint would be to put the world at my feet. The secretsof kings and courts would be mine， the machinations ofdiplomats and politicians， the play of stock-gamblers， theplans of trusts and corporations. I could keep my hand onthe inner pulse of things and become the greatest powerin the world. And I—” He broke off shortly， then added，“Well， I have begun my experiments， and I don’t mindtelling you that I’m right in line for it.”
A laugh from the doorway startled us. Paul Tichlornewas standing there， a smile of mockery on his lips.
“You forget， my dear Lloyd，” he said.
“Forget what？”
“You forget，” Paul went on— “ah， you forget the shadow.”
I saw Lloyd’s face drop， but he answered sneeringly， “Ican carry a sunshade， you know.” Then he turned suddenlyand fiercely upon him. “Look here， Paul， you’ll keep out ofthis if you know what’s good for you.”
A rupture seemed imminent， but Paul laughed goodnaturedly.
“I wouldn’t lay fingers on your dirty pigments.
Succeed beyond your most sanguine expectations， yetyou will always fetch up against the shadow. You can’t getaway from it. Now I shall go on the very opposite tack.
In the very nature of my proposition the shadow will beeliminated—”
“Transparency！” ejaculated Lloyd， instantly. “But it can’tbe achieved.”
“Oh， no； of course not.” And Paul shrugged his shouldersand strolled off down the briar-rose path.
This was the beginning of it. Both men attacked theproblem with all the tremendous energy for which theywere noted， and with a rancor and bitterness that mademe tremble for the success of either. Each trusted me tothe utmost， and in the long weeks of experimentationthat followed I was made a party to both sides， listeningto their theorizings and witnessing their demonstrations.
Never， by word or sign， did I convey to either the slightesthint of the other’s progress， and they respected me for theseal I put upon my lips.
Lloyd Inwood， after prolonged and unintermittentapplication， when the tension upon his mind and bodybecame too great to bear， had a strange way of obtainingrelief. He attended prize fights. It was at one of thesebrutal exhibitions， whither he had dragged me in orderto tell his latest results， that his theory received strikingconfirmation.
“Do you see that red-whiskered man？” he asked，pointing across the ring to the fifth tier of seats on theopposite side. “And do you see the next man to him， theone in the white hat？ Well， there is quite a gap betweenthem， is there not？”
“Certainly，” I answered. “They are a seat apart. The gapis the unoccupied seat.”
He leaned over to me and spoke seriously. “Betweenthe red-whiskered man and the white-hatted man sitsBen Wasson. You have heard me speak of him. He is thecleverest pugilist of his weight in the country. He is alsoa Caribbean negro， full-blooded， and the blackest in theUnited State. He has on a black overcoat buttoned up. Isaw him when he came in and took that seat. As soon ashe sat down he disappeared. Watch closely； he may smile.”
I was for crossing over to verify Lloyd’s statement， buthe restrained me. “Wait，” he said.
I waited and watched， till the red-whiskered man turnedhis head as though addressing the unoccupied seat； andthen， in that empty space， I saw the rolling whites of apair of eyes and the white double-crescent of two rows ofteeth， and for the instant I could make out a negro’s face.
But with the passing of the smile his visibility passed， andthe chair seemed vacant as before.
“Were he perfectly black， you could sit alongside himand not see him，” Lloyd said； and I confess the illustrationwas apt enough to make me well-nigh convinced.