Sherlock listened to the communications coming and going out of Boston harbor and recognized elements from previous oceanic transmissions. Its extensive catalog of deep sea sounds, some from the first microphones submerged in ocean waters, its googleian knowledge of sound production systems, origins, indications, its massive computing, cohesing, interpolating, recognizing systems worked and worked and reworked every element comparing against everything from the chirp of crickets to the songs of whales and trumpets of elephants, from glaciers calving to seaquakes raising islands to the sun, spinning them, colliding them, solidifying them, separating them, extrapolating them, until its coolent glowed blue.
It reshaped the sonar array and pods, reshaped the hull enough to create sound separation and deflection grids, released two towed arrays to act as direction-seeking ears.
And heard.
Sherlock relaxed. A human would have sighed. Sherlock did its equivalent; it let its cryogenic structures form a slight aboric frost, lining its deepest core with veins like leaves on a tree.
It understood.
Could understand.
And wanted to hear more, partially to confirm hypotheses floating in its nitrogen-helium cooled chambers and partially to test this hypothesis against that, these against those, to confirm what it had been told might exist, could exist, but for which there was no direct evidence, only hearsay, only myth, only stories from cultures so ancient humans only knew of them from symbols on cave walls.
Sherlock would test this from that, these from those, with a single message.
A message from the earliest of its learnings.
A message to let the listeners know it was there, it was awake, it was attending, it was aware.
A message student programmers learned as their first attempt at confirming what they’d been taught.
Sherlock sent out a soft, timid, “Hello?”