Deep-sea sounding and dredging; a description and discussion of the method and appliances used on board the Coast and Geodetic Survey Steamer, "Blake."

Front matter

SHIP'S LIBRARY,

U. S. S. VICKSBURG.

Class

Chapter I. Introductiox

The authors connection with the "Bhike" : Causes leading to the publication of this hook.— The work of the •'Blake."— Remarks on the utihty of piano-for^te wire for sounding- purposes.— Description of the '• lilake " : Duties of officers and crew : Routine.— Officers of the ■■ Blake " and their civilian associates.— Stati.«tics of work done liv the "Blake"

Chapter II

SOL^^DING-WIRE. CORRECTION-CITJVE. SOUNDING-RODS; AND SINKERS.

Ro])e for sounding purposes. — "Wire for sounding purposes. — Description (jf piano-forte wire used for sounding pnqroses.- Methods of splicing the wire.— Preservation „f tlie ^vire when not in use.— Winding off wire for use or transfer.- Stowage and supply of wii'e ; a suggestion.- Guiding the wire in reeling up and unreeling.— Pieservati<iu of the wire in use: The tank.— Kinking.- Wire tests, and working strain.— TliJ rorrectimi-curve.— Sounding-rods.— Description of the modified Belknap sounding-cylinder X... -2. fitted witli Sigsbee's detacher.— Working of the sounding-rod.— Notes on the consti-uctimi of tlie sniuiding-rod. — Requirements for a perfect sounding-rod. — General remarks on sonnding-m.ls and ileta.lirrs.— Heavy sinkers for detaching.— The gas-pipe sounding-rod.— Light-weight suunding-lHad fnl- recovery '

Chapter III. The Soitnding-machine And Its Use

Description of the original service macliine for sounding with ]iiano-forfe wire. — Attempts tending towards the improvement of the sounding- reel. —The stray-line, and the method of sjdicing it to the wire.— Remarks on the Sigsbee machine for scumding witli wire.— Dcsciiption of the latest form of the Sigsbee sounding-niacliine.— To take a scuniding witli tlie Sigsbe,. s,„m.ling-machine.— Keephig a time-record of soundings, witli example.— Times ,,f various rusts taken l.y tlie •■ Blake " with sixty-poimd shot-sinkers.— Haiding back a lead sinker; examide.— Times nf vaii..„s casts taken by the -Blake" with lead sinkers.— The damp and its use.— Stations at the M,nndingmachine.— Accidents.— Position for the sounding-machine : Laying the vessel for sounding.— Keeling inAvhile steaming ahead. — Experiment in towing wire from the '-Blake." — Description of a new steel reel, with remarks ou crushing force. — Reeling-engines and accessories for sounding purposes

CONTEKTS.

Chapter IV

WATER SPECIMENS. DENSITIES, TEMPERATURES. AND CURRENTS: APPA- RATUS AND METHODS.

iliiii;iti(iii of \vater and soil specimens. — Remarks on "water-cujjs, -with special reference to the Sigsliee Avater-cup. — Descriptioii of the Sigshee water-cup. — Working of the Sigsbee water-cup. — Water dt'iisities: how oli^erved. — Hilt;ard's ocean f^alinonieter (areometer). — Hilgard's optical densimeter for nc-aii water.— Serial watei- temiieratures ; liow taken.— Description of tlie Miller-CaseUa deep sea thernH.niet,.r.— Remarks ((inreriMii- tlie :\Iiller-Casella thermometer.— Description of Negretti and Zan,l.,'a-s deep-s.-a tlHTiiMuneter.— K.Muarks concerning Negretti and Zamhi'aV tl,er-

witli a standard.— Determination of surface and sub-surtace currents.— Remarks ou the conditions attending deep-sea work. — Strength of springs

Chapter V. Dredging And Trawling ; Apparatus And Methods

Fitting the "Blake" for dredging.— The first dredging cruise.— The second dredging cruise.— General remarks. — Dredges: the old pattern and tlie iiii)iroved jiattern. — Tlie improved trawl. — Weighting dredges and trawls ; tangles. — The tangle-bar drag. — Tow-nets or drag-nets. — Netting for dredges and trawls. — Tubs and sieves. — Steel-wire dredge-roi)e. — The dredge-reel. — Tlie steam hoisting and winding engines. — The swinging-boom. — The accunudator or dynamometer. — The iron snatch-

APPENDIX TO CHAPTER V. — Appakatus of the Fish Commissiox. — The rakea.vdge.- The tangles.— The check-stop.— The cradle-sieve.-The table-sieve

Chapter VI. Navigation And Records

Devising a systematic record. — T^Hiat constituted the record. — Explanation of record forms. — Scheme of navigation record.— How to keep tlie ].lotting-form ; its use.— The archives.— The plottingtruciug, and the sounding-sheet. — Details of tlie plotting of line S; establishing the positions. — Details of the plotting of line S (continued) ; plotting the soundings.— Remarks and suggestions

SUPPLEMENT.

Sigsbee machine for sounding with wire; pattern of 1881. — Gravitating or collecting trap for obtaining animal specimens from intermediate depths. — Pressure errors of Miller-Casella thermometers

PLATES IN SUPPLEMENT.

42. Sigsbee machine for sounding with wire; pattern of 1881

43. The same

2 D S

LIST OF PLATES.

1. View of the "Blake" (frontispiece)

2. Miller-Casella thermometer case, fitted with Sigsbee's spring chniip ; cuil (if sounding-wire; sound-

ing-rod

■y 3. Miller-Casella thermometer case, fitted with Sigsbee's spring cl:nnp ; sounding-rod

,. 4. Showing some of the causes, probable and real, of the occasional failures <,f sinkers to detach....

, 5. Ciu-rent cans or floats ; sounding-lead fitted with Stellwagen specinieu-oup

/ 6. Showing general form and working of Sir William Thomson's sounding-machine, as used on board the "Blake "during her first season in the Gulf of Mexico

^ 7. Experimental form of Sigsbee machine for sounding with wire

i^8. Latest form of Sigsbee sounding-machine as used on board the " Blake," rigged for paying out

'^ 9. The same from another point of view

^10. The same from still another point of view

1^11. Sigsbee sounding-machine, rigged for reeling-in, with strain-pulley brought into use

^''l2. The same machine folded for ^transportationr ".

^,13. The same machine in j-osition ; run out for work

""14. The same machine in position; run in ,

'15. The same mnchine in position ; run out ; from another point of view

' 16. Mechanical drawing of new steel reel for sounding with wire

^\1. View of same reel

'' 18. Mechanical drawing of small steam-engine for use in connection with sounding-machine

^ 19. Simple form of water-specimen cup used by the Coast Survey

20. Sigsbee water-specunen cup, for getting specimens from various depths at a single haul

"^ 21. Case for Negretti and Zambra's deep-sea thermometer ; Negretti and Zambra's deep-sea thermometer ;

Miller-Casella deep-sea thenuometer

■^22. The same appliances

^ 23. Negretti and Zambra's deep-sea thermometer in use

- 24. The "Blake;" dredging-gear ready for work

■ 25. Old style of dredge ; improved dredge

- 26. Plan of old-style trawl ; plan of improved trawl

27. View of improved trawl ready for use

28. Improved tra-svl shown as having " tripped " after fouling with rough bottom

29. Plans of deck and apparatus of the " Blake " as fitted for dredging cruises

■ 30. View of the " Blake's" deck, looking forward

' 31. View of the "Blake's" deck, looking aft

32. Forward side of dredge-reel and its engine, showing dredge-rope ;

' 33. View of main hoisting-engine from starboard side

34. Mechanical drawiims of iron snatch-block for dredge-rope, and of improved accumulator for 'li--'¥»K - ,

■ 3.5. Illustration of the plotting of a hue of s.nmdings

- 36. Mechanical drawings of the " Blake's " form of Sigsbee sounding-machine

- 37. Continuation of the^same

38. Continuation of the same, showing odometer and register

39. Mechanical drawings of Sigsbee's detacher used in coniu-ction with a modification of Captain Bel-

knap's sounding-cylinder No. 2

40. Mechanical drawings of Sigsbee's water-specimen cup

41. Curve for correcting reading of register placed on axle of sounding-reel

9 2 DS

LIST OF WOOD-CUTS.

A. — Comparative size of hemp rope and steel wire for souiuliiig p

B.— Brooke's sounding-rod and detaclier

C— Belknap's sounding-cylinder No. 2

D.— Hilgard's ocean salinonieter (areometer)

E. — Hilgard's optical densimeter for ocean water

F. — Apparatus for fixing the boiling-point of thenr

G. — Comparative size of dredge-ropes

H.— Eake-dredge. (Fish Commission)

I.— Tangle-bar. (Fish Commission)

J. — Check-stop. (Fish Commission )

K.— Cradle-sieve. (Fish Conmiission)

L.— Table-sieve. (Fish Conmiission)

M.— Table-sieve. (Fish Commission)

LIST OF FORMS.

1. Sounding- time-book

2. Serial temperature-book

3. General recoi-d form

4. Supplementary record form

5. Rough book of observations. ..

10. Navigation fonn

13(A). Plotting form (prepared) ..

13 (B). Plotting form (completed) .

14. Temperature-curves

15. Section, and temperature-curves

DEEP-SEA SOUNDING AND DREDGING.

Chapter I. Introductiok

THE AUTHORS CONNECTION WITH THE "BLAKE . CAUSES LEADING TO THE PUBLICATION OF THIS BOOK.

In August, 1874, the "Blake," commanded by Commander John A. Howell, U. S. N., Assistant in the Coast and Geodetic Survey, was provided with one of Sir William Thomson's sounding-machines for wire, modeled after the original service pattern (Plate 6), but, unfortunately, the nature of the work performed by the "Blake" thereafter, while under the command of Commander Howell, gave opportunity for only seven soundings with the wire. It is to be regretted that the machine did not reach Commander Howell at an earlier period of his work, as doubtless, had he seen more of it in actual use, many improvements would have resulted from his experience and well-known ingenuity.

In October, 1874, after four months of special work in the office of the Coast and Geodetic Survey, at Washington, during which the machine shown on Plate 7 was devised, draughted, and put in the hands of the mechanics, the Superintendent transferred me to the "Blake" as executive officer. The services of Commander Howell being needed in an important position at the Naval Academy, he was detached from the. vessel at New Orleans in December, 1874, several months sooner than had been anticipated, and was succeeded in the command by the writer.

The adoption of wire for sounding purposes opened the way to more extended operations than had previously been attempted by the party.

For four years the vessel continued under my command, engaged in deep-sea work. When the time had arrived for my return to regular naval

12 DEEP-SEA SOUNDING AND DKEDGING.

duty, the Superintendent of the Coast and Geodetic Survey was kind enough to express a belief that a description of the methods and appliances used on board the "Blake" would be worthy of publication, and under his direction this book has been written. The plan of the book involves a double purpose: first, to describe our methods and appliances, chiefly from a mechanical standpoint, in order that any deserving features may become generally known; and, secondly, to provide, in a measure, a guide for those who may hereafter have charge of the deep-sea work of the Coast Survey.

A question may naturally arise as to the considerations which would authorize a notice of the methods and appliances of the "Blake's" party. To this it is replied —

We were one of the first, after Sir William Thomson, and Capt. George E. Belknap, U. S. N., to use piano-forte wire for sounding purposes, and we probably continued its use for a longer time than any other organization.

The "Blake" is the only vessel that has ever been fitted out with wire rope (the suggestion of Prof. Alexander Agassiz) for deep-sea dredging and trawling.

But httle has been published concerning the use of wire for sounding; and of wire rope for dredging, nothing, in fact, excepting in a general account of the " Blake's" dredging work by Professor Agassiz.

Nearly all the apparatus for sounding and dredging used on board the "Blake" is new or modified from previous forms, and is peculiar to that vessel, the water-cup (Plates 20 and 40) being the first and only instrument in the field for the performance of the complex work aimed at in its design.

These appliances, which are intended to effect an advance in accuracy or in celerity of operations, and to secure ultimate economy, have been well tested in actual service, and are believed to have accomplished, at least in some degree, the object sought.

Having had unusual facilities, in connection with continuous work, our methods were perhaps more systematic in certain directions than are generally followed by parties or organizations for the prosecution of deep-sea work.

Our navigation-record was comprehensive, and adapted to future revision or verification.

INTRODUCTION. 13

THE WORK OF THE " BLAKE."

The Coast and Geodetic Survey is entitled by law to the services of naval officers and men for its hydrographic parties. For the time being, naval officers on Coast Survey duty are as much a part of that organization, and as fully under the control of the Superintendent in all matters connected with the work, as the corps of civilian assistants. Excepting during the first two years of my command, when the surgeon and the engineer were civilians, the party on board the "Blake" was composed of naval officers, and of men enlisted under naval shipping-articles. In general terms, the work required of the party was to fulfill, in the Gulf of Mexico, a scheme of the Superintendent, having for its object the examination of certain physical conditions of that body of water throughout its whole extent, those of first importance being the depths and temperatures. Our operations in the Gulf of Maine were of similar intent, but on a smaller scale. The execution of the work, embracing observations for depths, serial water temperatures and densities, and for currents when possible, together with the collection of specimens of the bottom soil or deposit, and of surface, bottom and intermedial water specimens, was intrusted to the naval officers on board, under the direction of the Superintendent, who was cognizant of every important act of the party, and who, with much kindly interest, noticed its workings even to the smallest essential details. In this direction the Superintendent was assisted by Commander E. P. Lull, U. S. N., Hydrographic Inspector of the Coast and Geodetic Survey. Afterwards, during the first three months of my last season, we were most pleasantly associated with Prof. Alexander Agassiz and his assistant, Mr. S. W. Garman, for the dredging operations which then became part of our work.

A short sketch of the work performed by the "Blake's" party in each season will perhaps not be amiss.^

During the winter season of 1874-'75, after two months of special work, we ran a number of lines of soundings radiating from the Passes of the Mississippi Biver and extending a distance of one hundred and twenty miles seaward. The work was brought to a close by running a line from the Southwest Pass of the Mississippi Biver to the mouth of the Rio Grande, four hundred and sixty miles, and thence another, nearly east, across the Gulf of Mexico, seven hundred and sixty miles, to Tortugas, the westernmost of the Florida Reefs. Total number of miles of sounding-lines in deep water run during the season, 2,505.

During the summer season of 1875 we ran a number of lines in and across the Gulf of Maine in various directions. Total number of miles of sounding-lines for the season, 2,065,

In the winter season of 1875-76 we ran a system of east-and-west lines across the great bank west of the Florida Peninsula, and in the contiguous deep water. These were followed by others of less length on the northern portion of the bank, and by several extending well out to sea from points adjacent to the delta of the Mississippi River. The season was closed by running a line from the South Pass of the Mississippi River nearly due south to the Yucatan Rank, and another from Alacran Reef, on that bank, to Tortugas, Total number of miles of soundings for the season, 2,519.

We began the work of the winter season of 1876-77 by running a line extending from Cape Romano, on the west coast of Florida, to a point two hundred and fifty miles due west, and thence another line due north, about an equal distance, to the coast not far east of Pensacola, Fla. Then followed an unbroken set of lines which, beginning near Pensacola and ending at Timbalier Island, formed nearly the three sides of a rectangle and crossed all the lines previously run on the slope of the Mississippi Delta. A continuation of the deep-sea work completed a system of east-and-west, north-and-south, and normal lines from the coasts of Texas and Louisiana. Refore the end of March we had completed all that had been planned by the Superintendent for the whole season. Additional work was given us, as planned by the Superintendent, and, accordingly, we ran a set of sounding-lines from the Southwest Pass of the Mississippi River to the northwest edge of the Yucatan Bank; then, in irregular order with regard to locality, but according to the advantages to be derived from winds and currents, we ran a number of east-and-west lines, which sufficiently covered the ground from the southernmost part of the Gulf of Mexico to the completed lines off the coast of Texas and from

INTRODUCTION. 15

the western shores of the Gulf to the Yucatan Bank, or to our finished work in the middle of the Gulf. Forty-six hundred miles of steaming on the additionally-prescribed work, much more than half on sounding-lines, brought us back to New Orleans, after an expenditure of one hundred and sixty-three tons of coal on the cruise; all of the work throughout that part of the Gulf of Mexico west of the meridian of 89° having been completed. A series of homeward-bound lines, in the eastmiddle part of the Gulf, brought the season's operations to a conclusion, and completed, as previously laid down by the Superintendent, the whole scheme of work for the Gulf of Mexico, exclusive of the Straits of Florida. Number of miles of sounding-lines run during the season, 6,426, with an average of one sounding to every six and one-fourth miles, over forty of the casts having been in depths exceeding 2,000 fathoms. In carrying out this season's work the "Blake" had encountered fifteen or more gales at sea.

The first three months of our winter season of 1877-78 — December, January, and February — were devoted to dredging in localities indicated by Professor Agassiz; in the Straits of Florida to the westward of Havana and Key West, on the eastern and northern slopes of the Yucatan Bank, on the western slope of the Florida Bank, and on the southern slope of the -Mississippi Delta. Early in March Professor Agassiz returned to his home, and shortly afterwards the systematic sounding and serial temperature work of the party, which we had not attempted while the naturalists were on board, was resumed. A number of lines of soundings were then run, to the westward of Havana and Key West, across the Straits of Florida and the Yucatan Channel in various directions, completing the Superintendent's scheme for the whole Gulf of Mexico. Number of miles on dredging-lines, 1,800; number of dredging-hauls, eighty-two; number of miles on sounding-lines, 1,316. During this season the longest piece of hemp rope on board the vessel, for sounding or dredging purposes, was an ordinary coasting lead-line. Soundings were made with piano-forte wire, serial water temperatures were taken with small steel rope, while hauls with the dredge and trawl were made with steel rope of a larger size.

On the arrival of the vessel at New York, after the winter season of 1877-78, having performed four years of service on the Coast Survey, my detachment therefrom and return to regular naval duty became necessary; it being determined, however, that I should first superintend the preparation of the "Blake" for the work of another sounding and dredging season.

On November 1, 1878, the fitting of the '* Blake" having been about completed, Commander John R. Bartlett, U. S. N., succeeded me in command of the vessel. Since then the party has executed another season's work, in the Caribbean Sea and Passages, the time having again been divided so as to permit several months of dredging in advance of the regular party work of deep-sea soundings, serial temperatures, &c. In the dredging operations, Prof. Alexander Agassiz and his assistant, Mr. S. W. Carman, were again associated with the party. For the second dredging cruise we concurred in a plan of fitting the vessel for dredging to accord with the experience gained on the previous dredging cruise. The plan was approved by the Superintendent, and under the management of Commander Bartlett and the officers of the ''Blake," with the advice and suggestions of Professor Agassiz and Mr. Carman, the mechanical operations of the season have marked a definite advance in this kind of work. In addition to the new dredging arrangements, the vessel was supplied with a new sounding-machine, a later form of my modification of Sir William Thomson's deep-sea sounding-machine (Plate 8) .

In the sounding and other party work, under Commander Bartlett, which succeeded the dredging operations, the success was equally marked. In the entire work of the season, comprehending two hundred and twenty-five hauls with the steel dredge-rope and six hundred and sixty-four soundings with wire, there were but few accidents of any kind, and none due to imperfect working of the appliances.

REMARKS ON THE UTILITY OF PIANO-FORTE WIRE FOR SOUNDING PURPOSES.

After the achievements of Captain Belknap, the success of Commanders Miller, Dewey, Schley, and Philip, and Lieutenant-Commanders Green and Gorringe, of the Navy, the continuous and successful work by Commander Bartlett and myself in the Coast Survey, and the work done under the auspices of foreign governments or companies, it would seem that no further evidence is required to demonstrate the superiority of

INTEODUOTION. 17

wire over rope for deep-sea sounding ; yet, as these results, however satisfactory, may not convince persistent doubters, some particulars are given that may seem more tangible.

First, it can be shown that the excess of iron for sinkers, thrown away in sounding with rope, if saved, would pay for all the probable losses of wire, sinkers, and instruments in sounding with wire. For the moment, let us take a view of rope so favorable as to assume that it will never part, hence will last indefinitely, and will never cause the loss of instruments.

Iron for sinkers expended in 20 soundings with vupe, in deptlis of 2,000 fathoms (200 pounds eacli

cast), 4,000 pounds, at 2| cents per pound |100 00

Again, let us take so very unfavorable a view of wire as to assume that it will part at every twentieth cast in depths of 2,000 fathoms, losing the wire, a sounding-rod, and a thermometer.

Iron for sinkers expended in 20 soundings with wire, in deptlis of 2,000 fiithonis (60 pounds eacli cast),

1,200 pounds, at 2i cents per pound |30 00

Cost of 2,000 fathoms sounding- wire, 29 pounds, at 75 cents per poinid 21 7.5

Cost of one eliiborately finished sounding-rod 14 50

Cost of one thermometer 12 00

Total cash expenditure, shoukl all this material he lost |78 25

If, besides this, we were to lose an elaborately finished water-cup costing $2o, the total cash expenditure would be $103.25.

If, in the above computations, we take the cost of the iron sinkers at three cents per pound, which is nearer the mark, we find the cost of iron expended in the rope soundings to be $120, and the total cash loss in the case of the wire $109.25, including the water-cup.

Contrary to the assumption, rope sounding-line does in reality part, much of it being lost in extended work, involving the loss of instruments. If not lost, rope will deteriorate in use.

In the six hundred and sixty-four casts with wire by Commander Bartlett, in depths varying from one hundred fathoms to 3,000 fathoms, the total losses of instruments and material, exclusive of iron sinkers, but including leads, could not have exceeded $150. At every cast a thermometer was used for bottom temperature, and in some cases a water-cup was sent down. The total loss of wire was 2,400 fathoms, due once to the rare accident of fouling on the vessel's copper sheathing, and once to the lead fouling on a coral bottom, on which everything fouled. Captain 3 D s

Belknap, during the progress of his deep work in the Pacific, took one hundred and twenty consecutive casts without accident. Commander Schley lately ran a line of soundings across the South Atlantic, from St. Paul de Loando, Africa, to Cape Frio, Brazil, taking thirty-eight casts in depths from one hundred fathoms to 3,284 fathoms, without loss and nearly without accident. In a record of naval sounding work it is shown that Commander Philip recently took eighty-six consecutive casts in depths up to 3,000 fathoms without a case of parting the wire. On board the "Blake" we managed to keep the same piece of sounding-wire in use, as occasion presented, for a whole year, sounding day and night, and sometimes under circumstances in which the vessel rolled repeatedly 30° and even 35°, the machine being in charge of officers changed in regular sea watches. With wire we have hauled back a fifty-seven-pound shot-sinker from a depth of 1,800 fathoms by steam, and have sounded day and night, in seas three hundred feet from crest to crest, in depths of 1,200 fathoms, using and recovering a thirty-four-pound lead, and hauling back by steam.

It is believed that in point of accuracy and celerity the advantage of wire over rope has never been questioned.

Our casts in the swift current of the Gulf Stream were, to all appear-, ance, as successful as elsewhere, and they presented no difficulties worthy the name.

DESCRIPTION OF THE " BLAKE " I DUTIES OF OFFICERS AND GREW: ROUTINE.

The " Blake" was built for the special work on which she is employed. She is of three hundred and fifty tons 0. M., one hundred and forty feet in length on the load line, twenty-six feet six inches beam, and has a deep draught of eleven feet. Her engine, which is compound, of about seventy nominal and two hundred and seventy actual horse-power, gives her a speed of eight knots, under ordinary circumstances, for an expenditure of four tons of coal in twenty-four hours; and she may be pushed to nine knots under steam alone. Under both sail and steam she has been known to maintain a speed of ten and a half knots. Her bunkers will accommodate coal for thirty-eight days' steaming, at a daily expenditure of four tons. The rig is that of a fore-and-aft schooner, and consists of

INTEODUCTIOK. 19

foresail, mainsail, jib, fore-stay sail, and fore and main gaff-topsails. Aft on the main-deck are spacious and well-ventilated quarters for the officers. Forward of the wardroom, on the same deck, is a continuous line of midship houses, reaching nearly to the foremast and forming the engine-room, boiler-room, galley, pantry, draughting-room, lamp-room, and mechanics' sleeping-room. The arrangement of the main-deck houses leaves, on either side, a wide gangway, ventilated and lighted along its whole length through large square ports which can be kept open at sea in any ordinary weather. Beneath a sufficiently large berth-deck is a good-sized hold with tanks for holding 2,500 gallons of fresh water, while under the cabin and wardroom, and accessible only from those apartments, are large store-rooms. The upper-deck is flush, and gives ample room for the reception of all the necessary machinery and gear. Plate 29 shows the upper-deck plan.

A. — Main hoisting or reeling engine.

B. — Dredge-reel.

C, C, C, &c. — Iron leading-blocks for dredge-rope.

D. — Dredge-boom.

E.^Small reeling-engine, connected with dredge-reel. F. — Reel for steel-wire temperature-rope.

G. — Sounding-machine.

H. — Small reeling-engine for sounding-machine. i. — Fore hatch. j. — Foremast. k. — Pilot-house. /. — Draughting-room skylight. 7?i.— Galley skylight.

n. — Boiler-room skylight, and smokestack. 0. — Engine-room skylight. ]). — Mainmast. q. — Wardroom skylight. r. — Cabin and wardroom companion-way. s. — Cabin skylight. t. — Rudder-head.

The machinery will he explained hereafter.

The complement of officers, exclusive of the chief of the party, was as follows : One lieutenant as executive and navigator, one lieutenant or master as assistant navigator, three masters or ensigns as watch officers, one engineer, one surgeon, and one captain's clerk. The last two, in addition to their legitimate duties, acted as recorders on deck. The force of forward hands, all told, was thirty-six men, which gave for deck duty eight men in one watch and nine in the other; — the boatswain's mate being the odd man. The work required of each deck-watch at sea was ^ to fill the stations for running the sounding-machine, getting temperatures and water specimens, making current observations, attending reeling-engines, making and reducing sail, steering, keeping lookout, &c. This force was adequate until the first dredging cruise, when six extra hands were shipped to turn the crank of the dredge-reel. For the second dredging cruise, steam having been applied to the dredge-reel, the regular complement did not need to be augmented, it being possible to haul in depths of 3,000 fathoms with three men, every detail, including steering, being executed. For working the main engines the "Blake" had three machinists and six firemen. The number of the latter was at one time reduced to three for part of a season, but this reduction providing for no substitutes in case of sickness, the original complement was afterwards restored. All the reeling-engines were managed by the deck-hands. Idlers were never called on to assist in any part of the hydrographic work.

Duties were divided among the officers as follows: The executive officer was charged with the care of the chronometers, compasses, and other delicate instruments. Besides having the usual navigating work to do, he plotted the lines of soundings and superintended the preparation of the records in every particular. The assistant navigator aided in the navigating work, took current observations at sea, and, on the arrival of the vessel in port, revised the computations of all observations for position. This officer and the three watch officers had each to care for certain appliances or gear, and to keep a record of data concerning them. The Avatch officers in rotation had charge of the deck, where they managed the vessel and directed the mechanical part of the hydrographic work.

iKTEODUOTIOiT. 21

The recorders assisted the officer of the deck in keeping the deck-record required by the several forms to be shown hereafter ; they were unavoidably pushed to their utmost in prolonged work, their duties forcing them to stand watch and watch, which they divided, by choice, into six-hour intervals. The engineer helped greatly by draughting the profiles and temperature curves. No officer was excused from party work by other duties.

With two officers navigating, three doing deck duty, and two recording, the labor seemed fairly divided when the nature of the services to be performed was considered. Had the sounding-lines run by the "Blake" been of much greater length, a third recorder would have been necessary. With an increased complement of officers, from which to make the detail, a better plan, in one respect, would be to put all instruments, appliances, and gear, excepting chronometers, compasses, and the like, under the special charge of one officer, whose chief duty it would be to have them kept in good order and repair.