^, ^^^11^ IMAGE EVALUATION TEST TARGET (MT-3) 6^ -^ 4^ W 1.0 I.I l^|2£ |25 ii« Bii |22 ^ tiS. 12.0 Mlli 1.8 IL25 III 1.4 VI 0% vi /: "^14 ^1^ '/ /A PhotDgraphic Sciences Corporation «x^ SJ iV \ \ ?^^\ 4^1% ^^^ 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 '/. CIHM/ICMH Microfiche Series. CIHM/ICMH Collection de microfiches. Canadian Institute for Historical Microreproductions / institut Canadian de microreproductions historiques C Technical and Bibliographic Notes/Notes techniques et bibliographiques The Institute has attempted to obtain the best original copy available for filming. Features of this copy which may be bibliographically unique, which may alter any of the images in the reproduction, or which may significantly change the usual method of filming, are checked below. 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Maps, plates, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent 6tre fiimis A des taux de reduction diffdrents. Lorsque le document est trop grand pour dtre reproduit en un seul clichA, il est film6 d partir de I'angle supArieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images nicessaire. Les diagrammes suivants illustrent ia m^thode. 1 2 3 32X t 2 t • • f NOTES ON THE DJUSTMENTS of the UUMPY LEVEL INCLUDING OBMS OF FIELD BOOKS AND TABLES FOR [|EDOClN(i FBEf(CH AND ENGLISH MEASU1|^E, FOR THE USE OF SURVEYORS. BY W. McLKA WALBANK, B.A.S. I'KoviNt lAi. Land Si'Kvkvoi^ and Cuii. Knmnkkk. Montreal, P. Q. .... .... .\. ^ • ••',•• • • • • • • • • • • ..... 'a • * • • ... • • • ... PREFACE. Thp: object of the following remarks on the adjustments of the Dumpy Level is to enable Surveyor's Clerks and others who have not the advantage of a University edu- cation to understand how to test their instruments and make the necessary corrections without being obliged to purchase expensive works on the subject, or to depend upon the catalogues of the various instrument makers for their information, as it is seldom that the maker's adjust- ments are of practical use to the surveyor in the field. Hoping these notes may prove of interest. I am. Yours truly, W. McLk.v Walhank, B.A.S., P. L. Surveyor and Civil Engineer^ Montreal, P. Q., April, 18S3. 37707 HINTS TO STUDENTS. It is of the greatest importance that the line of Colli- mation should be parallel to the bubble tube. For ordinary levelling operations it is not of such importance if these two are not exactly perpendicular to the vertical axis ; but t is essential that the bubble should be in the centre of its run when a reading is observed. Always bring the centre of the lens on to the staff in reading. In taking a series of important levels instruct the staff holder to move the staff gently to and fro, the least reading observed will be the correct one. After reading the staff and noting the reading in your book, look to see that the bubble is still in the centre of ts run, and read once more as a check on the first reading. ■ Do not try to take longer sights than will admit of eading the staff distincdy. ^- Adjustments of the Dumpy Level. The adjustments of a level may be divided into two classes : Temporary and Permanent adjustments. The Temporary adjustments recjuire to be i)erformed with every change of tlie instrument, while in a well made instrument the i)ermanent adjustments seldom become deranged, but ought nevertheless to be tested every time it is used (/. <^.) each day. V TKiMPORARY ADJUSTMENTS. l5t ADJUSTMENT. To place the vertical axis truly vertical, wliich is commonly termed le* aig the instrument, and is per- formed as follows : Set up your instrument as nearly level as possible, by means of its legs or tripod. Set the telescope (which carries the spirit level) over two of the i)arallcl plate screws, and bring the bubble to the centre of its run by means of these screws, then turn the telescope through i8o degrees. If the bubble remains in the centre of its run, the instrument 6 is in adjustniciU; if not, correct ( i4) one half the apparent error by the plate screws and the other half by the screws attached to the bubble tube, (I say "apparent error," because the bubble indicates double the true error when it is thus reversed end for end.) 'J'urn the telescope {}() one-quarter round on the vertical axis and bring the bubble to the centre of its run as before; now turn it another {}() ([uarter, and the telescope will be over the same pair of screws as in the first instance. Again bring the bubble to the centre of its run and turn the telescope i8o degrees as already described. If the bubble does not now remain in the centre of its run, correct by the i)latc screws and the bubble tube screws in the same manner as already described. Keep on repeating the foregoing operations until such time as the bubble retains the centre of its run, while the instrument is being turned on its vertical axis through a comjilete revolution. The adjustment is then complete. 2nd ASJUSTMENT. To correct for parallax or make the foci of the object glass and eye-piece coincide : Move the eye-piece backwards and forwards until the cross-wires are seen distinctly, direct the telescope to some well defined object, and by means of the screws for that ^ ^> purpose move the inner iiil;c in and out until the image of theol)ject is ch.-ar and sharp, and apparently coinciding with the cross-wires. Test your adjustment by moving; y(jur head from side to side and at the same time lookin-' dirough the telescope. W the adjustment is complete the object will appear fixed, if imperfect the image will waver with the motions of the head. If the image appears to travel in an oi)posite direction to the movements of the head draw the inner tube out, if it moves in the same direction as the head it must be drawn inwards. 'J'his adjustment reciuires to be made anew for every object sighted to. PKRMANKNT ADJUSTMENTS ARK: FIEST To place the cross-wires in the axis of the telescope tube. This is a complicated adjustment and belongs rather to the instrument maker in making the instrument than to the practical Surveyor, for it has been shown that the exact coincidence of the intersection of the cross-wires with the axis of the telescope is not essential to accurate levelling. SECOUD To make the line of Collimation parallel to the bubble tube : Select a tolerably level piece of ground, drive in three good solid pegs at equal intervals, say about 150 feet, set 8 up your iiisUuniunt exactly over the centre peg. Perform the icinijorary adjustment as already described ; direct the telescope to a statlf held on one of the i)egs, focus and read it, taking care that the bubble is in the centre of its run and that no parallax exists, then direct the telescope to the staff held on the other peg, taking exactly the same jnecautions. The difference between these readings gives the difference of level between the top of the two pegw. Now that we know the difference of level between the top of the two pegs, we also know the readings on each start" which is on the same level. Remove the instrument behind one of the pegs and place it in the same straight line as the two pegs and as close to one i)eg as will admit of its being focussed. It now remains to make the line of Collimation ; trace a " level line " when the bubble is in the centre of its run. First read the staff nearest the instrument, and having got this, we know what the other staff ought to read if the line of Collimation is parallel to the bubble tube. Focus the the other staff and read it, if the reading on this staff is on the same level as the reading on the nearer staff, the line of Collimation is in adjustment, if not, get a reading on this staff on the same level by raising or lowering the Col- limating or diaphragm screws, watching at the same time 9 that the bubble remains in tlic centre of its run. This may aUer the reading of tlie near staff, so read it once more, and then read again tiie otlier staff. If the second reading on the further staff is on the same level as the second reading on the nearer staff the adjustment is com- plete, if not, continue rejieating the above operation until two readings on the same level are obtained with the bubble in the centre of its run ; when this is done the instrument is in perfect adjustment. Or, if the instrument has no diaphragm or Collimation screws, having found the difference of level of two bench marks, as already explained, and shifted the level to a position beyond one of them, alter, if necessary, the inclina- tion of the telescope by the plate screw.s, until the readings of the staves gives the true difference of level, and bring the bubble to the centre of its run by means of the screws attached to its end. N.B. — Care should be taken to see that the telescope is screwed tightly to the horizontal bar before commencing the permanent adjustments. The following are the forms of Field Book generally used by surveyors. In my own practice I always use the first form, it being in my opinion the easiest and most complete method of keeping field notes. 10 ( I'll st Form.) "Grand Mkrio Falls." Lkvkls fok ihi; "Canada Pulp Factory." Mai-f]; Mid, 1883. - — — .. _.._ Stations Dist'nc* . 15auk Iiiter- I'orc:- Heii;ht of , Kechu.etl Sljrllt. iiicdiatt -• SiKht. Instriiint;!! t Level. re.makks. i 67 -2( ii.AL on Crib lower eiui marked in 1-27 10-08 68-47 ! 58-39 1 red chalk. 1-30 59 • 69 1 9-57 0-60 50 - 1 2 < >n Surface Water lower end. i 59 • 09 10-18 ;{-(ii 69-27 : ^u^ • m 7-82 2-35 73-48 71-13 (.i,Mven Mr. P.attle.) W.M. Lower cut Cold Chisel m.ark 10-58 0.14 73-34 i'>..\L on Stone, Head of Lower 83-92 78 • 65 on supposed IJ.AL IKxcavation. 7-21 3-58 76-71 Red arrow on centre line Lower HO -34 IJench of l'^"d "f Upper .Section 0»88 83-04 Upper Section. 13-68 0-47 96-72 96-25 11-86 • 64 108-il 107-47 8-65 116-12 12-50 5-52 103-62 [mark (given P)attle.) H.AL on Upper Section Cold Chisel 2-19 1 1 • 60 H.I^L on Cuard Wall. 112-79 10-19 102-06 1-36 12-81 103-96 91-15 Surface water on new Centre Line IMar. -^ 68-89 i 14-94 67-20 44-94 1 i 23-95 23-95 ff^ 11 83. (Second Form.) - — - — . \ ill ilk. Dist'iicc Station O Hack •Siglit. Inter- mediate. Front Sight. Ri^ Fall. Reduced Level. R KM ARKS. No. 1 1 lOO-OO 15. iM. on S. \V. corner of ] -20 IhoiiMc at cross-roatls. 100 1-70 9-10 7-90 92.10 1 .'{0 4-30 2 -GO 89-50 390 9-60 7-90 84.20 e.) irk 570 1-10 1-00 8-70 7.60 76.60 ler 720 5-20 4.20 72-40 on 't<, H90 No. 2 8-90 9-60 8-60 68-00 H. M. on paiapet of bridge over stream. 1040 l-io 7-80 75-80 9.10 \ 1190 1360 1510 8-70 4-30 i 3-10 1-90 4-80 6.00 6-80 80.60 81-80 88-60 =.) 6-20 ;el 2670 No. 3 4-20 2-00 90-60 H.M. on large stone junc- 9-40 [tion of fences. 37-90 • 47-30 37-90 100-00 • I - - — 9-40 12 Lineal English Feet to French Feet. Eng. Feet. 1 2 3 4 5 6 7 8 9 Units. Tens. 0-94 9-38 1-88 18-77 2-81 28-15 3-75 37-53 4-69 46-91 5-63 56-30 6-57 65-68 7-51 75-06 8-44 84-45 Hundreds 93-83 187-66 281-49 375-32 469-15 562-98 656-81 750-63 844-46 Thousands. 938.29 1876-59 2814-88 3753-17 4691-46 5629-76 6568-05 7506-34 8444-64 Tens of Tliousands. 9382 18765 28148 37531 46914 56297 65680 75063 84446 •93 -86 •79 •72 •65 -58 -51 -44 •37 3820 English Feet, how many French Feet ? 3000 = 2814-88 800 = 750-63 20 = 18-77 i Eng. Feet 3820 = 3584-28 Fr. Feet. 13 Lineal French Feet to English Feet. 1 Fr. Feet Units. Tens. Hundreds. Thousands. Tens of Thousands. 1 1.07 10-66 106-58 1065-77 10657-65 2 2.13 21-32 213-15 2131-53 21315-30 3 3.20 31-97 319-73 3197-30 31972-95 4 4.26 42-63 426-31 4263-06 42630-60 5 5.33 53-29 532-88 5328 • 83 53288-25 6 6.39 63-95 639-46 6394-59 63945-90 7 7.46 74-60 746-04 7460-36 74603-55 8 8.55 85-26 852-61 8528-12 85261-20 9 9.59 95-92 959-19 9591-89 95918-85 1082 French Feet, how many English Feet ? 1000 1065*77 000 000*00 80 85-26 2 2-13 French Feet 1082 1153-16 English Feet. 14 " Superficial " French Arpents to English xVcres. Arpents. Units. Tens. Hundreds. Thousands. 'I'ens of 'I'liiHisands. J '2 0-84 1-09 8-45 10-90 84-49 108-97 844-85 1089-70 8448-51 10897-02 ;'. 2 • 53 25-:}5 253-46 2534-55 25345-53 4 .'} - .-^8 33-79 i 337-94 3379-40 33794-04 r> 4 - 22 42-24 422-43 4224-20 42242-55 5-07 50-09 ! 500-91 5069 - 1 1 50691-00 i 5-91 59-14 1 591-40 5913-90 59139-57 8 0-76 07-59 1 075-88 0758-81 67588-08 9 7-00 76-04 1 ] 700-37 7603-66 70036.59 Remarks. In a farm or lot of 3198 Arpents, how many Acres? 3000 =- 2534-55 100 = 84-49 90 = 76-04 8 = 6-76 Fr. Arpents 3198 2701-84 Eng. Acres. 15 "Superficial" English Acres to French Arpents. Knglish ' Acres. I'liits. Tens. Htiiulrecls, 'l'lloils;ill(K Tens (if riiDiisaiicls. 1 1 -18 II -84 ll8-3r: 118;!-04 I 1830-41 2 2-37 ■2-i-i\7 230-73 2307-28 230 72-8'' 3 •) • -.r> ■',-, ' :, 1 35") • 09 3550-92 .".5509- ''3 4 ! 4-73 47 -ur) 473-47 4734-50 473-15 -01 5 6 7 5 ■ 92 7-10 .")!»• 18 71 -02 591-82 710-18 5918-21 7101 -85 59182-05 71018--JO 8 • 29 82-85 828-55 8285-49 82854-87 8 9-47 94 -fig 940-91 9409-13 94091-28 9 1 • (If) I on •;-)?, 1005.28 10052-77 lO0527-O:t llKMARlvS A field contains 3,551 Englisl, Acres, how many Frcnck Arpents does it contain ? 000 3550-92 500 591-82 50 59-18 1 1-18 Eng. Acres 3551 = 4203- 10 Fr. Arpents. * t 11.3 16 " Excavation and Embankment." l^arth transferred from excavation to embankment loses from one eighth (^) to one tenth (ji^) of its volume. Rock increases its bulk or volume when broken by about (y-,) one third. " Masonry. , » One toise = 72 French Cubic Feet. " " =87-16 English " " One quarry toise = three (3) toises of Masonry. 11'- « • e t f > 17 PLANS, SURVEYS. Architectural Designs, &c. ACCURATELY REPRODUCED BY T^ SHR'i^ TO ANY SIZE. GEORGE BISHOP & CO. 169 ST. JAMES STREET, MONTREAL, And WTINNIPEG, Man. 1^" Estimates furnished by mail. n t 18 ESTAHLISHF.D 1 85 7. HEARN & HARRISON, MANUFACTURERS OF Surveyors' Instruments 242 & 244 Notre Dame Street, MONTREAL, P. Q. ID N. B.— Ilepalrs promptly exeevited. f I*