"As a preliminary measure, might it not be a good idea to gain some idea as to our present line of flight?" Crane asked dryly, bending a quizzical glance upon his friend. "You know a great deal more than I do about the hypothesis of linear departure of incompatible and incommensurable spaces, however, and so perhaps you already know our true course." "Ouch! Pals, they got me!" Seaton clapped a hand over his heart; then, seizing his own ear, he led himself up to the switchboard and shut off the space drive, except for the practically negligible superimposed thirty-two feet per second which gave to the _Skylark's_ occupants a normal gravitational force. "Why, Dick, how perfectly silly!" Dorothy chuckled. "What's the matter? All you've got to do is to--" "Silly, says you?" Seaton, still blushing, interrupted her. "Woman, you don't know the half of it! I'm just plain dumb, and Mart was tactfully calling my attention to the fact. Them's soft words that the slatlike string bean just spoke, but believe me, Red-Top, he packs a wicked wallop in that silken glove!" "Keep still a minute, Dick, and look at the bar!" Dorothy protested. "Everything's on zero, so we must be still going straight up, and all you have to do to get back somewhere near our own Galaxy is to turn it around. Why didn't one of you brilliant thinkers--or have I overlooked a bet?" "Not exactly. You don't know about those famous linear departures, but I do. I haven't that excuse--I simply went off half cocked again. You see, it's like this: Even if those gyroscopes could have retained their orientation unchanged through the fourth-dimensional translation, which is highly improbable, that line wouldn't mean a thing as far as getting back is concerned. "We took one gosh-awful jump in going through hyperspace, you know, and we have no means at all of determining whether we jumped up, down, or sidewise. Nope, he's right, as usual--we can't do anything intelligently until he finds out, from the shifting of spectral lines and so on, in what direction we actually are traveling. How're you coming with it, Mart?" "For really precise work we shall require photographs of some twenty hours' exposure. However, I have made six preliminary observations, as nearly on rectangular coördinates as possible, from which you can calculate a first-approximation course which will serve until we can obtain more precise data." "All right! Calcium H and calcium K--Were they all type G?" "Four of them were of type G, two were of type K. I selected the H and K lines of calcium because they were the most prominent individuals appearing in all six spectra." "Fine! While you're taking your pictures I'll run them off on the calculator. From the looks of those shifts I'd say I could hit our course within five degrees, which is close enough for a few days, at least."