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August, 1920 To Land Men on Dock A landing pole designed by the chief - engineer, J. Brand, of the Great Lakes bulk freighter Aucustus B. Wotvin, is illustrated in the accompanying drawing. As pointed out in The Bulletin of the Lake Carriers' association, the WotvIn's ship safety committee believes the in- stallation to be unequaled in point of safely landing men on the dock and at the same time eliminating striking the dock with the steamer's bow. The industrial committee of the Lake Carriers' association has recommended that landing poles be installed on all ships after being subjected to a test of 800 pounds. The Wotvin installation, as worked gut by Mr Brand and Capt. John Tower, master, is designed to hoist weights up to 1200 pounds from boats alongside. or out of the cargo hold through No. 1 hatch. The pole illus- trated, or more properly the derrick, is, of course, much heavier than would be required simply to land a man on a dock. The committee of shore captains after examining the details of the land- ing pole recommended the use of an additional block to give greater purchase and insure added safety. The lower block shown is the one added on recom- mendation of the committee. How Sounding Tubes Are Used Physical laws': underlying the scale of a sounding tube. are discussed in a paper recently issued by the United States coast and geodetic survey. The author is Walter D. Lambert, geodetic computer. The use of the sounding tube or depth recorder has long been recog- nized as a convenient and_ rapid method for getting approximate soundings in depths of 100 fathoms or less. It has never been an_in- strument for accurate surveying and, indeed, the depths shown by two tubes of different patterns, thrown overboard at the same point, or even by two tubes of the same pattern, have often exhibited surprising dis- crepancies. The larger discrepancies must be due to some accident in the working of the apparatus, but the smaller ones may be due to the dif- ferent assumptions made. in laying off the scale of depths used. More- Over, it does not appear that the method of graduating the tubes now On the market has ever been pub-. lished in detail, It is the purpose of this paper: . to provide, with the information : and, as correct a scale as possible or the tubes of the new coast and Seodetic survey pattern; (2) to give 4 THE MARINE REVIEW a method for correcting the depths read directly from the scale for varia- tion in temperature and in atmos- pheric pressure; (3) to provide a compilation of physical data likely to Prove convenient in a further study of ithe subject. _ An approximate formula is first de- rived and corrections are given for the departure of the air from a per- fect gas and for the vapor pressure and the compressibility of water; the final formula is put in.a convenient form for computing tables from it. The amount of compressed air dis- solved in the water of the tube is considered in the light of the data available and of the mathematical 479 tioned simpler formula) for correct- ing the readings for variation of temperature and pressure and a table showing the difference between a scale computed on the assumption of no absorption of air by the water in the tube and a scale computed on the assumption of absorption of air up to the saturation point. The use of some of the tables is illustrated by numerical examples. More than 225,000,000 tons of ship- ping, steam and sail, harbor, coastwise and deep water, have been drydocked in the big repair yards owned by the Todd Shipyards Corp. in New York harbor and: on the Pacific coast. This LOrM foes -- Ling Collar Vil Lolfed a7 pipe x QQ. 5% 40 bolied through Optighi® SOV1G0 Pt SACU Screwed an (00 3 Live lasyae 2 Dipe 2 LY0e 10570 F Ol pe e YW easily removed ( i Pe-cvear See 7 ww 2" Lye 19'Long/ WeBVY 1" FEC TGO0 LH ED 7 Deck \ AM GLOVE 1400S WO TIP LIEN _>» Socks | ee he. Wer --- DERRICK TYPE OF LANDING POLE INSTALLED ON STEAMER A. B. WOLVIN theory of absorption. Simple ap- proximations are given for correct- ing the readings for deviation from the assumed normal temperatures and pressure; more accurate correction formulas are also deduced and com- pared with the simpler ones, which are shown to be sufficiently accurate unless extreme precision is demanded. Other minor corrections are also con- sidered. The tables at the end contain a compilation of data on the physical properties of air and sea_ water. Special tables are included for the density, vapor pressure and com- pressibility of sea water and oi the, absorption of atmospheric gases by it, a table of water pressures at various depths, a general table for the scale of a sounding tube, a spe- cial table for tubes of the coast and geodetic survey type, 4 table (com- puted according to the above men- total is more than four times the mer- chant tonnage of the world ai the end of 1919. These 225,000,000 tons, repre- senting vessels of every size and type, have been handled by the 19 Aoating docks and the two graving docks that. are distributed among the various Todd yards. Four shipping board steamers--the EASTERN 'TEMPEST, EASTERN GLADE, West Tocus and OTHo, have been as- signed by the shipping board to clean up the 1919 grain crop at Portland, Oreg., and on Puget sound, according to an- nouncement made by the division of operations. Iceland has 155 registered vessels aggregating 17,944 tons. The largest craft of this northern island is the steamship Guttrtoss of 1414 tons. This craft has docked at New York several times during the last few years.