CHAPTER I A Strange Offer SDCTOR Hackensaw, I'm looking for a place." "I'm sorry, my friend, but we have no vacancy at present." "My name is Phessenden Keene. Al- though I left school at the age of fifteen, I have studied at home and have the equivalent of a college education. I am very anxious to study inventing, and having heard a great deal about your marvelous inventions, I should like very much to work for you," "I'm sorry, hut as I said before, there is no va- cancy at present. In fact, this is the dull season and I have more men on hand now than I know what to do with." Phessenden Keene smiled. "I know," said he, "that you have no vacancy for an ordinary man, but I am sure you have one for me!" Doctor Hackensaw looked up in surprise at this conceited statement and was about to make an angry reply, but a look at the clean-cut, intelligent features of the young man before him, caused him to hold his tongue. The young fellow evidently had a strong will, for he continued: "I know my own value better than you know it. I am so sure that you have a vacancy for me that I am willing to come to work for you for nothing." "Thank you," replied Doctor Hackensaw, coldly, "but I desire to pay my assistants for their work. Besides, as I said before, there is no work for you to do." "I'll find work," replied the young man confi- dently, — "and plenty of it. Besides, I am willing to do all the dirtiest and most disagreeable work on the place. I will black the boots, clean out the spit- toons or the drains, attend to the furnace, shovel snow and so on. I will be your porter and carry heavy bundles for you to any part of the city." i the i 2 and are not to receive a cent in M13S Pep Speaks "•"^ IVEhimat I -=- Pop," whis 'V^fl ed Miss I i trial, hisper- Pep Perkins, who, seated at her typewriter, had over- heard the conversation and was pleased with the young man's looks. "How can you live if I don't pay you any sal- ary?" asked Doctor Hack- ensaw of the young man. "I have a couple of hundred dollars laid by that I saved penny by penny from my wages on a ranch, where I worked f or a while. I can make that last me for a year, and I know that long before that time I can convince you that my services are invaluable." "And if I am not convinced?" "In that case, I won't ask for anything." "Very well, I'll engage you on your own terms. You are to do all the hardest and most disagreeable TUfAKINC om's self iiivi.'iiile hax always been one of "■& the great fascinations io the human race. And no wonder I Imagine all the mischief we could make, all the eavesdropping zve could do, and all the secrets we could unravel! Scientifically speaking, it is not impossible to make a body invisible. Recent experiments made by a New Eng- land professor of chemistry show that when certain liquids are injected into organic tissues, they become practically transparent. The professor succeeded m making small animals entirely transparent and practically invisible. Who knozvs that in the future, by some means of chemicals, combined with certain rays, i! may not be possible for its In iiii.'/ij- onrsche. 1 ; entirely invisible? We are sure you will enjoy the latest Dr. Hackensaw Exploit of the Invisible Girl. Bozo zvould YOU catch an, invisible person? But nothing is impossible to Dr. Hack- ensaTi', so see how he did it! work o return." ' "Thank you," "When will you begin?" "Bight away ! I see the windows in the next room haven't been washed for a month. I'll begin by cleaning those—" and five minutes later, provided with a pail of water and a rag, the young fellow was industriously polishing away at the windows, which soon shone as they had never shone before. "Well, Pep," asked the doctor, "what do you think of that young fellow and his proposition?" "I don't know what to think, but I like his looks." "So do I. But for all that he may be a burglar, and may be choosing this means to learn where all the valuables on the place are kept. I have mil- lions of dollars worth of unpatented ideas that an intelligent chap like him could steal." "He looks like an honest fellow." "Looks don't count for much. The only other ex- planation I can see for hia offer, is that he has fallen in love with you, Pep, and has chosen this way of coming near you." And Doctor Hackensaw smiled mischievously. "Nonsense!" cried Pep, blushing, but seemingly not at all displeased with the idea. Whatever the reason, young Keene soon made his services veritably invaluable. He came early and stayed late and worked industriously all the time. One of his first jobs was to make a grand house-cleaning. Boom by room he went over the whole establishment, opening every neglected cup- board and cleaning it thoroughly. He timed hia work so well, and did it so neatly as never to occa- sion discomfort to anyone. He did more. He made a card catalogue of every document and every ob- ject in the place with a hieroglyph, to indicate where the thing was to be found. It was soon learned that if anyone wanted some particular thing, there was no sense in hunting for it, for Keene could lay his hands on it in a minute. B c CHAPTER II The Z-Ray Photograph OCTOR HACK- ENSAW, I've got something peculiar to show you !" The speaker was Phes- senden Keene, bronzed from sunburn, and just returned from a trip to Central Africa, where lie had been sent on a confi- dential mission by the doctor. Keene was now Doctor Hackensaw's right-hand man. His declaration that he would make himself indispensable was no vain boast. Before he had been in the doctor's service a week, it was evident that he was a man of extraordi- nary abilities and energy. Doctor Hackensaw, how- ever, in order to make the test thorough, kept him at work a whole month, without any salary. At the end of that time, he made him a princely offer for