Conspicuous among the devices developed, orginally for anti-submarine purposes, but certain to bei'invaluable fo shipping under peifce conditions, is tho hydrophone—an instrument which detects under-water vibrations set up by a moving vessel. Microphones and magnetophones of exceedingly high sensitiveness were employed, sometimes with attachments which enabled the listener to ascertain the direction from which the disturbance was coming. The "silent submarine" was, nowever, introduced to circumvent the hydrophone, and this development was countered by the echo mothod," under which a beam of sound was sent out by chasing the vessel, eireeping the seas like a searchlight, and causing an echo when it strikes a solid object, such as a sub marine. The echo method can al?o bo used for sounding, for locating icebergs, surface vessels, and rock-bound coasts in « fog.
gUSBa-BBB&OBBBBBf.Bafl.BQjag "■Lam. Ono cube of lvelcon « IB Ml "' hlllf *P int ot boiline water, and n jfflfljl W >■ cup of ■wholoaonio loop it ready, • 5j V >~ in Iha licit liever- gg _V \ £ \ a ? c tor colli 'toy - o it v\ T!r~' - wa rm» find in- pf "ffr-V X/_afcl# viiroraioMtrcneth. 0 V __TBS_: fflBM m " n(1 "onrishM. ' VT TKITiHiiB Ilimheencnce/__J— *> VT) ffg| r, ot prime bqcf O 111 b_->— with flnnly-unt vege- sr J jjj Ml v tohlei, and contains ne !*"■> \S. H chemlcali. "oy 311 I Yc g • cubei for lOd, At all J, IS. m[ grociri—try on» jflfflfea^^i ©STP!» OT», QARQLt OR SWALLOW
Permanent link to this item
https://paperspast.natlib.govt.nz/newspapers/DOM19200813.2.10.2
Bibliographic details
Dominion, Volume 13, Issue 274, 13 August 1920, Page 3
Word Count
234Page 3 Advertisements Column 2 Dominion, Volume 13, Issue 274, 13 August 1920, Page 3
Using This Item
Stuff Ltd is the copyright owner for the Dominion. You can reproduce in-copyright material from this newspaper for non-commercial use under a Creative Commons BY-NC-SA 3.0 New Zealand licence. This newspaper is not available for commercial use without the consent of Stuff Ltd. For advice on reproduction of out-of-copyright material from this newspaper, please refer to the Copyright guide.