Actual or projected routes for telegraph cables across the deep sea have also been sounded with extreme accuracy in many cases; but beyond these lines of sounding the vast spaces of the ocean remain unplumbed save for the rare researches of scientific expeditions, such as those of the " Challenger," the " Valdivia," the " Albatross " and the " Scotia."

While top-end and mid-range are handled well, once again however the lower ends of the sound spectrum are left sadly unplumbed.

But there are also unplumbed depths in the clarity of this writing.

Actual or projected routes for telegraph cables across the deep sea have also been sounded with extreme accuracy in many cases; but beyond these lines of sounding the vast spaces of the ocean remain unplumbed save for the rare researches of scientific expeditions, such as those of the " Challenger," the " Valdivia," the " Albatross " and the " Scotia."

While top-end and mid-range are handled well, once again however the lower ends of the sound spectrum are left sadly unplumbed.

But there are also unplumbed depths in the clarity of this writing.