HARVARD UNIVERSITY H Library of the Museum of Comparative Zoology Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vol. LV. No. 1. GEOLOGICAL SERIES. Vol. IX, No. 1. HARVARD SEISMOGRAPHIC STATION. THIRD ANNUAL REPORT FOR THE YEAR, 1 AUGUST, 1910 — 31 JULY, 1911. By J. B. Woodworth. CAMBRIDGE, MASS., U. S. A.: PRINTED FOR THE MUSEUM. February, 1912. No. 1. — Harvard Seismographic Station. Third Annual Report for the year, 1 August, 1910 — 31 July, 1911. By J. B. Woodworth. The list of earthquakes and seismic disturbances of the ensuing table continues that published in the Curator's Report M. C. Z., 1909- 1910, p. 28-33. The numbers correspond to entries in the Record of Earthquakes kept at the Station from the beginning in 1908. For the times heretofore given in Eastern Standard Time of the 75th meridian west from Greenwich, the Greenwich Mean Time, from midnight to midnight, has been substituted and the data have been cast in the form of a monthly bulletin instituted during the year. The adjoined short table will facilitate the conversion of Green- wich Mean Time into that locally used. E. S. T. hours between noon and midnight are in italics. For the G. M. T. hours in italics, read the 75th meridian date as one day earlier. G. M. T. / 2 8 4 5 6 7 8 75° T. 8 9 10 11 12 1 2 3 G. M. T. 16 17 18 19 20 21 22 23 75° T. 11 12 1 2 3 4 5 6 7=7 The Gottingen system of nomenclature or symbols has also been adopted in place of the less readily written system of Laska heretofore mainly employed in the reports. This system is as follows: — P beginning of first preliminary tremors or longitudinal waves. S beginning of 2nd preliminary tremors or transverse waves. L beginning of long waves, main waves, or principal portion. M time of maximum motion among the long waves. C beginning of coda or trailers (seldom read). F end of visible motion. i impetus, initial motion well observed. e emersion, evident belated beginning of record. A amplitude of the maximum motion. With undamped pendulums usually given in millimeters; with damped pendulums in micra (/*). N stands for the north-south component of motion registered by the horizontal pendulum lying in the prime vertical (east-west). E stands for the east-west component of motion recorded by the pendulum lying in the meridian (north-south). 9 10 11 12 13 14 15 4 5 6 7 8 9 10 24= = 0 bulletin: museum of comparative zoology. Under the column of Remarks in the accompanying tables the fol- lowing abbreviations appear: — Q, (quake), for earthquake. Qf, a felt earthquake, the name of the place following indicating the approxi- mate origin of the shock. Ql, a local shock. Qr, earthquake reported. O, origin or epicentre. Dp, distance from Cambridge as indicated by the pendulums. Dm, distance from Cambridge measured on a globe. Micros., masked by microseisms. Latitude 42° 22' 56" N., Longitude 71° 06' 59" W. Greenwich; Altitude 5.367 M. Time: Mean Greenwich, midnight to midnight. Instruments: Two Bosch-Omori horizontal pendulums (mechanical registration) . No. Date Phase Time Per- iods s. Ampli- tudes Remarks 1910. h. m. s. nun. 80 Aug. 5 ePN ePE SN SE LN LE 1 39 04 1 39 01 1 45 23 1 45 10 1 52 18 1 52 42 D. ca. 2900 mi. MN 1 53 35 32.5 ME 1 53 57 7.0 FN 2 55 - 81 Aug. 11 PN PE SN SE 'LN LE MN 16 36 19 16 36 19 16 40 17 16 41 00 16 41 41 16 45 26 16 46 23 2.7 D. 1500 mi. •4 ME FN FE 16 47 15 17 33 17 35 20.5 82 Aug. 21 PN PE SN SE LN LE ME FN 5 56 27 5 57 18 6 03 18 6 02 05 6 11 30 6 12 22 6 13 08 7 24 8 .7 D. 3100 mi. woodworth: harvard seismographic station. Peri- Ampli- No. Date Phase Time ods tudes Remarks 1910 h m. s. s. mm 83 Sept. 1 PE LN LE ME FE 1 06 57 1 45 13 1 43 53 1 48 15 2 32 21 Probably Qf at Koshun in Formosa. D. 7700 mi. Dm. 7800 mi. 84 Sept. 4 LN LE 13 43 20 13 43 58 20 Not reported elsewhere. 85 Sept. 6 ?PN 20 14 21 5.5 Qf. at Andalgala, Cata- ?SN 20 23 32 6.8 marca, Argentine. Dm. 4850 mi. Qr. 20 h. 14 m. SE 20 23 43 10.0 Dp. 4850 mi. LN 20 41 24 17.5 LN 20 47 06 MN 20 50 10? 0.5 ME, A = 0.9 mm. FN 21 15 39 Ottawa P 20 h. 4 m. 27 s. FE 21 54 Strassburg ea. 20 h. 21.1 m. Possibly 2 quakes. 86 Sept. 7 PN PN LN LE FE 7 32 21 7 32 23 8 17 14 8 18 28 9 46 Ottawa P 7-31-49. 87 Sept. 7 LE F 10 42 07 11 11 Faint N-S; periods 15-16s. Qr. at Rilski- Monastir, Bulgaria. 88 Sept. 9 PN PE SN SE LN LE MN ME FE 1 24 15 1 24 09 1 33 05 1 33 03 1 48 01 1 47 20 1 52 45 1 51 10 4 14.5 23.2 Dp. 4600 mi. 89 Sept. 9 LE F 9 45 13 11 16.3 0.4 Very faint N-S. 6 bulletin: museum of comparative zoology. Peri- Ampli- No. Date Phase Time ods tudes Remarks 1910 h m. s. s. mm. 90 Sept. 9 LN 14 35 58 14.0 Not reported from Ot- LE 14 36 18 13.3 0.2 tawa. Qr. at Higiiey, FN 14 47 35 San Domingo at 13.55 91 Sept. 16 LN LE FN 19 28 20 19 27 14 19 41 14.0 13.3 el9.25.36 at Ottawa 92 Sept. 24 PN PE 3 39 22 3 39 21 D. 2500 mi. SN 3 44 56 9 Shocks reported at Flag- SE 3 44 56 13 staff and Kingman, LN 3 52 56 Arizona, this night. LE 3 50 28 O of this Q off coast of MN 3 55 24 3.0 Mexico? ME 3 52 35 5.5 FE 4 58 93 Sept. 24 eN FE 4 22 08 4 28 54 4 Superposed on Record 92. 94 Oct. 4 Oct. 5 PN PE SN SE LN LE ME FN 23 10 34 23 11 01 23 18 56 23 18 59 23 29 34 23 25 59 23 27 0 04 1.5 Qf. Antofagasta, Chile. Dp. 4350 mi. Ottawa P. 23-10-52. 94a Oct. 18 eLN LE ME F 3 48 20 3 39 55 3 50 4 .02 95 Oct. 30 SE LE FE 8 28 8 34 9 05 N-S micros. Qr. Scilly Islands, Eng. at ca. 8h. 96 Nov. 6 eSN SE 20 47 08 20 45 16 S in micros. woodworth: harvard seismographic station. Peri- Ampli- No. Date Phass Time ods tudes Remarks 1910. LN LE h. m. s. 20 51 29 20 51 31 s. mm. Qr. Nevada. MN 20 52 36 21 Strassburg eL 21h. ME 20 51 52 12 FN 21 50 97 Nov. 9 PN ?PE SE SE LN LE ME F 6 29 01 6 24 37 6 27 05 6 39 00 7 06 48 7 06 59? 7 08 30 9 06 5.25 PE = 6-24-07? Cf . Qf . in Aparri, N. W. Luzon, Phillipine Ida. at 2h. 54 m. (local t.). 97a Nov. 10 e LE 12 50 13 12 57 38 Qf . Fura, Japan, at 12h. F lost in micros. 98 Nov. 10 e LE ME F 13 16 43 13 22 49 13 32 39 14 09 5.5 N masked by micros. 99 Nov. 12 LN 18 29 48 Micros. LE 18 29 54 13 0.5 Cf. Qr. Prov. Mendza, FN 18 34 08 Argentine at ca. 15? hrs. e? 8 22 26 100 Nov. 14 LN 8 26 58 Qr. Taihoku, Formosa, LE 8 27 08 17-20 at 7h. 35m. MN 8 35 54 0.2 ME 8 34 54 0.7 FE 9 02 59 101 Nov. 15 LN MN FN 0 34 15 0 38 49 0 53 42 0.5 Oh. 30.3m. at Ottawa. 102 Nov. 15 eLN 14 45 54 12 LE 14 46 07 9 14h. 32m. at Ottawa. LN 14 49 46 17 8 bulletin: museum of comparative zoology. Peri- Ampli No. Date Phase Time ods tudes Remarks 1910. h. m. s. s mm. MN 14 55 33 1.0 Lurch to S. ME 14 55 36 1.3 " "E. F? 102a Nov. 25 LE F 19 15 15 19 16 33 Not reported elsewhere. 102b Nov. 25 LE F 20 08 16 20 11 24 Not reported elsewhere. 103 Nov. 26 ?PE 5 02 03 3 Micros. SE 5 11 45 10 Obscure record. ?SN 5 19 10 10 LN 5 45 02 Strassburg, P 5h. 00m. LE 5 43 01 41s. MN 5 46 2 ME 5 50 14 12.7 ME 5 51 01 14 Qf. Jeronimo, Spain, at F 5 40 4h. 50m. 104 Nov. 29 eLN eLE ME FN 3 30 24 3 29 27 3 39 29 3 53 13 16-20 22 0.4 Ottawa eLN 3h. 18m. 104a Nov. 29 LN LE FN FE 4 01 19 4 09 50 4 11 36 4 12 34 10 Possibly trailers of pre- ceding. 105 Dec. 4 eSN eSN 11 44 07 11 44 53 12 Ottawa llh. 43.5. LN 12 11 51 17 0.3 eLE 12 17 05 20 0.4 FN 12 51 15 106 Dec. 10 LE F 1 16 08 1 16 32 24 1.4 N not tracing. Not at Ottawa. Local disturbance? 107 Dec. 10 PE SE LE 9 47 06 10 04 26 10 09 10 woodworth: harvard seismographic station. 9 Peri- Ampli- No. Date Phase Time ods tudes Remarks 1910. LE ME F h. m. s. 10 23 51 10 46 12 30 s. mm. 2.5 108 Dec. 13 ePN SN 12 00 53 12 10 21 Ottawa P 11.56.10. Qf. Ujiji, Lake Tangan- SE 12 10 59 8 yika, at llh. 39m. LN 12 25 39 LE 12 22 21 16 MN 12 29 25 20.2 ME 12 33 32 17 F 14 50 108a Dec. 14 ePN ePN 21 04 59 21 05 14 Qf. in Scotland. Reg- istered in Paisley ca. SN 21 11 58 6-10 20 h. 54 m. SE 21 14 00 13-16 LN 21 27 53 Obscure record. LE 21 32 17 NoM. FN 21 58 08 109 Dec. 16 PE LE MN 15 02 39 15 24 17 16 00 53 N record tangled in diurnal waves. ME 15.55.19, 16.00.17. ME 16 05 47 4 Qf. Halmaheira, Mo- FE 17 10 55 lucca Ids. Batavia P 14 h. 49 m. 110 Dec. 16 e? 19 25 Obscured by micros. eLN 20 07 25 20 1.2 Not reported from Ot- F 20 27 tawa but 19h. 34m. to 20h. 20m. at Strassburg. 111 Dec. 20 SE LE 18 25 56 18 47 28 10 17 112 Dec. 21 SE F 10 40 10 58 N stylus caught on point in paper. E line tangled. Imperfect record of Ot- tawa P lOh. 31m. 113 Dec. 21 eP SE ?LE 13 06 11 13 09 19 13 13 06 Micros. N stylus tipped over on joint in paper before record began. 10 bulletin: museum of comparative zoology. Peri- Ampli- No. Date Phase Time ods tudes Remarks 1910. LE ?F h. m. s. 13 16 42 13 25 15 s. 14 mm. 114 Dec. 29 SN 14 05 13 14 LN 14 19 52 20-18 0.4 L-S = 4650 mi. Laska. F 14 40 Qf. in Elis, Greece; Dm. 4600 mi. 115 Dec. 30 eSN 3 38 03 LN 3 41 48 17-20 Ottawa P 3.26.42. LE 3 42 34 16 FN 3 59 53 1911. 116 Jan. 1 ?PN SN SE 10 41 41 10 58 58 11 02 01 17 Micros. LN 11 12 17 18 0.5 No maximum. LE 11 12 — FN 11 43 34 117 Jan. 2 ePN ?SN LN LE FN 11 09 08 11 33 56 11 36 10 11 37 26 11 57 34 20 E-W very weak. 118 Jan. 2 SE 23 50 38 LE 23 53 38 20 Qf. Lechaind, Greece, LN 23 54 26 20 23 h. 34 m. Jan. 3 ME FN FE 0 06 32 1 09 58 0 19 32 .5 119 Jan. 3 LN 8 14 22 .2 eLE 8 20 48 16-20 .1 F 8 35 120 Jan. 3 PN 23 38 50 3 Qf. Vernie and Issik PE 23 38 52 4 Kul, Turkestan. SN 23 49 30 28 SE 23 49 30 16 D. 6200 miles or 10000 woodworth: harvard seismographic station. 11 Peri- Ampli- No. Date Phase Time ods tudes Remarks 1911. h. m. s. s. mm. Jan. 4 LN LE 0 08 50 0 08 11 44 33 kms. MN 0 20 07 75 + Ran off drum 3 times. ME 0 15 75 + Ran off drum 4 times. FN 2 38 Both pendulums un- FE 2 35 damped. Motion of pendulum. excessive and irregular. 121 Jan. 7 LN 3 03 34 15-24 .3 P and S, if present, very LE 3 03 33 13-20 .15 doubtful. FE 4 09 52 122 Jan. 11 eLN 18 35 51 17-20 MN 18 36 33 .5 Record E-W like micro- FN 18 38 05 seisms. 123 Feb. 5 PN S L F 4 30 44 4 35 59 4 44 27 4 57 O = San Salvador (J. B. Goesse). 124 Feb. 6 eN FN eE FE 23 36 17 23 36 34 23 36 17 23 36 21 Ql. Local shock; felt at home in nearby house by observer. Not no- ticed by other people. 125 Feb. 7 ?SN 2 34 34 E-W not registered. N. L 2 35 42 12-20 0.25 tangled. O west of L 2 39 44 Cambridge. F 2 45 125a Feb. 16 eN L F 20 24 31 20 26 20 20 33 37 16 125b Feb. 17 eN F 2 52 19 2 54 05 125c Feb. 17 eN M 14 40 47 14 41 50 14-16 12 bulletin: museum of comparative zoology. Peri- Ampli- No. Date Phase Time ods tudes Remarks 1911. F? h. m. s. s. mm. After some mins. — in- definite. 125d Feb. 18 ?N 2 04 24 Pendulum tilted slowly e 2 05 29 5 toS. e 2 12 28 E-W Component (12s LN 2 13 29 14-15 period) undamped, not L 2 16 27 13 registering satisfac- F 2 27 torily. 126 Feb. 18 PN 19 04 59 Earthquake at Mona- E 19 04 35 ' stir in Macedonia. SE 19 24 31 ■ LN 19 30 07 E 19 32 36 MN 19 33 11 8.5 Undamped pendulum per. 24s. E 19 36 13 1.7 Undamped pendulum per. 12s. FN 21 34 E 20 20 127 Feb. 18 PN LN F 21 49 45 22 07 01 22 37 20 Cf. Strassburg P 21.35. 08. No record E-W. 128 Feb. 19 LN F 2 30 54 2 37 17-20 e 2.31.36 Ottawa. No record E-W. 129 Feb. 26 eSN 12 59 29 13 Ottawa, e 13.00.20. LN 13 05 43 24 No record E-W. F 13 23 130 Mch. 11 LN 4 15 25 16-20 Micros. M 4 30 02 0.5 Ottawa eL 4-14. F 4 53 47 No trace E-W. 131 Mch. 19 eP?N eS 4 31 39 4 37 59 4 42 41 3-4 22 20-28 LN 4 44 54 20 Dp. 2750 mi. woodworth: harvard seismographic station. 13 No. 132 133 134 135 136 137 Date 1911. Mch.20 Apr. 7 Apr. 7 Apr. 10 135a Apr. 18 May 4 May 5 Phase LE L LN FE FN LN F ?PN ?S L F SN L ?F PN S L F eLN L F Apr. 28 P S L F PN E SN E LN E FN Time h. m. s. 4 44 32 4 45 46 4 46 41 4 50 13 5 00 11 0 16 51 0 18 51 7 04 48 7 13 04 7 22 46 8 09 36 18 40 27 18 41 47 18 49 09 18 49 01 18 54 29 18 56 53 19 52 08 2 03 33 2 07 22 2 31 10 00 28 10 07 03 10 14 08 10 31 23 48 41 23 48 30 23 58 15 Peri- ods 13 16 16 16-22 12 17 12 16 4 8-10 18-20 28-30 4 12 12 3 4 18 23 58 06 20 Ampli- tudes mm. .25 Remarks Not reported from Strassburg. (19.5) Not shown E-W. Weak microseisms run- ning. Ottawa, e 7-03-42. E-W not working well. Qr. Sinaloa, Mex. ca. this time. Microseisms super- posed. D. 5090 kms. (W. &Z.). Qr. near Bogota, U. S. Col. Lost in Pendulunruhe. E-W not recording well. Distance about 3000 mi. E-W record illegible. D. 8670 kms. 0 07 48 0 06 07 1 35 Throw N 4.5 mm. then S 29 mm. (5 5) | Throw E 10.5 mm. then W8mm. F? Followed by several LL. (O = A152°30'E.4>51°) 14 bulletin: museum of comparative zoology. Peri- Ampli- No. Date Phase Time ods tudes Remarks 1911. FE h m. s 1 32 s. mm. N-(J. B.Goesse). 137a May 9 PN S L F 19 47 26 19 53 19 19 59 04 20 15 E-W not working, freely. 138 May 10 eLN 0 41 49 12 Began 0-23-36 Sta. E 0 44 26 12-14 Clara, Calif. F 1 138a May 11 LN F 5 17 05 5 43 28 Ottawa, e5-17. 138b May 25 PN S? 8 06 12 8 13 42 8 Not shown E-W. L 8 22 06 20 0.1 F doubtful. 139 May 31 e 19 03 10 Cf. Qr. at St. George, LN 19 05 23 20 Grenada, at 3.14 local L 19 14 time. 140 June 2 MN M F 20 48 10 20 48 14 20 48 38 1 0.5 Possibly local traffic jars but more pro- nounced than usual and ME 20 48 08 1 0.5 looks like local shock F 20 49 30 from sharp beginning of M. 141 June 3 eSN? 21 08 LN 21 23 51 20 .5 Ottawa LN 21-18.5. LE 21 26 02 FN 22 03 Strassburg 20-40-50 to FE 21 52 21-20. 142 June 7 PN PE SN SE LN LE 11 09 50 11 09 39 11 15 38 11 15 48 11 21 46 11 22 17 Qf. Mexico City to Colima. Dp. 2300-2700 miles. MN 11 24 39 75 Off drum. ME 11 27 08 75 it it woodworth: harvard seismographic station. 15 No. Date 142a 143 144 145 1911. June 15 June 15 June 16 July 1 146 July 4 147 14S July 12 Phase MN ME FN eSN L F PN PE SE LE F LN F SN L M iPN (e) LN LE FN FE ePN S L M F Time h. m. s. 11 11 38 04 5 43 41 5 46 13 6 05 14 39 57 14 39 44 14 52 44 15 13 40 16 50 — 18 12 17 18 31 46 22 13 13 22 20 47 22 21 16 23 13 - 13 46 28 13 48 37 14 27 56 14 27 28 15 08 15 05 4 26 52 4 38 26 5 07 53 5 16 38 6 29 24 Peri- ods 5 12 24-30 Ampli- tudes mm. 75 25-20 29 14 4.5 Remarks Off drum. tt a After 14-30, lost in local disturbances. Very faint. Ottawa 14-39-42. Strassburg 14-38-22. Ottawa P 22-07-07. D. 2600 miles. Qf. San Francisco, 2:01 pm. (local t.). Qf. Mt. Hamilton 2:00: 2 pm. Changed paper N-S be- tween 13-51-57 and 14-27-20. Changed record E-W between 13-16-30 and 14-48-37 Strassburg P 13-41-37. 4-45-57 pds. 13 20 Qf. Isle of Salibaboe, East Indies. BataviaP4h. 12m. 57s. Artificial record. 16 bulletin: museum of comparative zoology. Of the 83 recorded earthquakes in the above list, 25 or about 30 % failed to give a record of the preliminary tremors upon the times of beginning of which calculations for distance are based. That such records consisting of long or surface waves only are due to distant weak shocks is shown by their accordance in time with the occurrence of earthquakes frequently reported by the press. Such was the case for instance with that of 7 September, 1910, pertaining to the record of the earthquake at Rilski-monastir in Bulgaria, and that of 9 Sep- tember, 1910, whose origin was near Higuey, Haiti. It is probable that a few cases of such records have been overlooked either because of the small amplitude of the motion of the stylus or by reason of the record being masked at times when microseisms were running. The times of beginning of these long waves as given is presumably later than their appearance at the Station. A comparison of the times obtained at Cambridge and at Ottawa, where a photographic registration is used, brings out a frequent failure on the part of our instruments, recording on smoked paper, to give readings as early by some seconds as would be expected. In part this defect is undoubtedly to be attributed to the action of the sooty layer in which the needles work. Again the Ottawa Station is on or near bed rock while the pier at Cambridge rests on an unknown thickness of glacial sands and clays which exercise a damping effect on the preliminary vibrations. It is thus rarely possible to state that the first appearance of the P tremors represents the initial impulse of the seismic motion at Cambridge. One of the chief reasons for installing a seismograph in the Depart- ment of Geology was the hope that local New England earthquakes and small shocks might be accurately recorded. Since the implace- ment of the seismograph in April, 1908, several local shocks have been reported by the press as affecting eastern Massachusetts within a radius of 20 miles from Cambridge and thence outward to northern New Hampshire and eastern Maine. None of the local shocks re- ported in the daily press has left a recognizable trace on our records. The one local shock felt and recorded at the Station was not reported to the daily press. The New England shocks of which I have knowl- edge for the year ending 31 August, 1911, are as follows: — 21 August, 1910. The daily papers reported the time as lh. 45m. p. m., E. S. T. Lowell, Mass., and surrounding towns in the Merrimac valley felt shocks lasting several minutes. At Tyngsboro dishes were rattled several seconds and sounds like thunder were heard. A shock was distinctly felt at Chelmsford Centre. Explosive noises were woodworth: harvard seismographic station. 17 heard in Lowell in the sections known as The Highlands,Pawtucket- ville, and Belvidere. No damage. Not recorded at this Station. 30 August, 1910. At 9h. 30m. a. m., E. S. T., a shock was felt at Sunapee, N. H. Press accounts not seen. Not recorded at Cam- bridge. 6 February, 1911. Local shock felt by the observer at 51 Oxford St., Cambridge, Mass. Recorded on the seismograph at 6h. 36m. 17s. a. m., E. S. T. The N-S component was in rapid oscillation for 17 sees, probably from its own momentum. The shock felt by the observer seemed to travel from the northeast and to last not longer than one or two seconds. Apparently not noticed by others. The observer was lying on a couch on the first floor of the house. From local newspapers issued during the year covered by this Report 33 accounts of earthquakes giving place of origin and sometimes other data have been culled. These were shocks which would have been known before the introduction of seismographs. The number thus reported is 38 % of the number of earthquakes recorded at the Station for the same period. Of those reported by the press with mention of locality, etc., 18 were local or distant shocks not recorded at this Station. Of the total number of earthquakes thus made known, 101, the seismograph gave notice of the occurrence of 82.18 % and the local press reports 17.82 %. The efficiency of the Station has steadily increased from the begin- ning as the following tabulation of the number of earthquakes re- corded month by month from April, 1908, will show. Number of Earthquakes Recorded Monthly since 1908. Year. Jan. Feb. Mar. Apr. May. Jun. Jul. Aug. Sept. Oct. Nov. Dec. 1908 10 0 3 10 11 1909 100021343732 1910 5 2 5 5 12 9 8 4 10 3 11 12 1911 8 11 3 5 6 6 3 This increase is partly due to a closer reading of the records and greater skill in picking out seismic waves among the various wander- ings of the pendulums. The records for 1910 are in close agreement as regards number with those at the Dominion station at Ottawa. The discrepancies arise from long waves of distant earthquakes moving on paths near that of the great circle passing through both stations. A weak disturbance may pass through one of the stations and die out or become too faint for distinct registration at the other. 18 bulletin: museum of comparative zoology. The earthquake of 3 January, 1911, which was destructive about the shores of Issik Kul in Turkestan, was of the highest order of in- tensity producing prompt action on the part of seismographs installed on this continent at distances varying from 6000 to 7250 miles from the epicentral tract. The following table compiled from some of the data sent to this Station in the course of its exchanges serves to illus- trate the comparative working of the Station and to point out the necessity for obtaining the time of arrival of initial waves to a second. Distance. Station. P s L F 87° Seattle 6 38 30 6 49 06 7 06 50 8 16 00 88° Ottawa 6 38 36 6 49 16 6 55 40 9 50 91° Cambridge 6 38 50 6 49 30 7 08 11 9 38 105° New Orleans 6 42 30 6 52 7 16 30 9 09 30 The three stations first named are equipped with Bosch-Omori seismographs of different designs, that at Ottawa having photographic registration. The New Orleans station of the Jesuit Seismological Service has a Weichert seismograph. These four stations have been taken because the times show a manifest progression in general of the wave phases from north towards the south. An analysis of the rates of transit for the phases, however, shows that the seconds as given are approximations to anything like a uniform rate of transit. An- other difficulty lies always in estimating the distance correctly so that while the time may be read correctly for great distances the meas- ure cannot be given with the same degree of accuracy as the time of beginning of a wave phase at a station. It is from such data as these that the calculations of the velocity of propagation of seismic waves must at present be made. It is obvious that accurate time and frictionless devices for registering the initial motid'n of the seismographic pendulum are a prerequsite of satisfactory results at every station. The Messina earthquake of 27 December, 1909, was recorded during my absence from the University. Professor Rizzo of the Messina Observatory has shown that the times given in the Annual Report for 1908-09 begin with the second preliminaries instead of the first. On examining the record I find the first preliminary tremors present and confirmative of Dr. Rizzo's emendation. The first preliminaries were partly masked by microseisms. The revised record should then read as follows: — 75th M. Time West. N-S s 4 39 33 L 4 54 29 M 4 56 — F 5 55 s-w 4 54 31 5 02 25 woodworth: harvard seismographic station. 19 Vd. Memorie delle Reale Accaderaie delle Scienze di Torino, 1910, ser. 2, 61, p. 400. From a study of our records from September, 1909, to 31 August, 1910, during which period 40 cases of determined duration of the vibration of the pendulums at Cambridge gave a total of 47h. 35mins. 32s. On the supposition that the remaining 28 cases were of the same average duration, it appears that the ground was in that year agitated by distant earthquakes Tooths of the time. Microseisms. At most seismographic stations and particularly at those on or near the coasts of a continent the phenomenon known as microseisms are recorded characteristically as small vibrations of about 5 sees, period. They may last for two days or more. At Cambridge they are almost invariably the accompaniment of some cyclone moving to or off the coast, a feature first described by Dr. Klotz of the Dominion Observatory at Ottawa. Rarely microseisms have appeared at Cambridge during a period of fair weather but chiefly when incoming vessels report heavy gales to the eastward in the North Atlantic. These vibrations are nearly wanting during the summer months; but from October onward well into the spring microseisms are recorded for one or more days about once a week. The cause of microseisms has not yet been sufficiently investigated to make it certain that they are in every case set up by the same agency. The hypothesis that they are initiated by the surf beating on the shores of the seas finds support in Europe in the apparent increase in the duration and intensity of the microseisms towards the coast. At this Station microseisms are a frequent source of great uncer- tainty as to the time of beginning of the preliminary tremors of a distant earthquake and a small percentage of what would otherwise be good records are thus annually lost, though the main waves of the records are but little affected by microseisms. A typical case of microseisms superimposed upon waves of a longer period is thus described in the Station journal for October, 1909. About 5h. 33m. a. m.,. 15 October, 1909, microseisms and waves of irregular periods varying from 30 to 60 seconds began, and con- tinued on both components until ca. lh. 51m. on 18 October, the microseisms continuing until between 8 and 9 p. m., 18 October .... At the same time there developed a cyclonic storm of great fury in Alabama, Tennessee, etc., which passed eastward and out to sea .... The weather maps show that during the microseismic storm with long flat waves from 15-19 October there was prevailing a "high" baro- metric area over the southern Appalachians and a "low" over the 20 bulletin: museum of comparative zoology. New England region .... Similar conditions were repeated during the microseisms of 25 and 26 October, 1909. Another case is that of the microseisms of 24, 25 November, 1909. A heavy cyclonic rain and snow storm passed over Cambridge. There was a slight fall of snow during the night of the 23-24th, followed by frozen rain and snow during the day of the 24th, turning to heavy rain at 8 p. m., the 24th. Cloudy and dull on a. m. of 25th. Mi- croseisms began between 6 and 7 p. m. the 23rd and continued to the morning of the 25th, being strongest during the 26th at height of the storm. Period of tremors from 5. to 4.53 sees. On 29 November, 1909, a bad gale in Boston harbor and off the coast was reported, the wind rising to 72 miles an hour, — also felt on the shores of Cape Cod. During the day both components of the seismograph registered waves with periods of 15 to 30 seconds, up to 4 p. m. The long period "pulsations" it is generally thought are local wind effects. They occur at Cambridge sometimes when no marked local winds are blowing. Inasmuch as it appears most probable that the regular diurnal swingings of the pendulums depend upon temperature and baro- metric changes of little immediate geological import no attempt has been made to tabulate the data to be derived from a study of the records. The same is true of the longer period wanderings of the pendulums which are associated with the passage of cyclones. The phenomena are rather pertinent to meteorology than to a direct study of earthquakes, though undoubtedly the barometric and the ther- mometric data thus to be obtained may throw some light on the conditions which affect the earth's crust at times of seismic distur- bance. Where heavy damping of the pendulums is resorted to for the proper control of the seismograph as an instrument, of precise measure- ment of the movement of an earth-particle, these meteorological effects are nearly if not quite eliminated from the record. From the geo- logical point of view microseisms are likewise of little interest except so far as in common with other short period vibrations of the earth's crust characteristic of the preliminary tremors of seismic waves they may promote changes of state in the loosely compacted sediments or in magmas near the point of solidification. Doubtless these vibra- tions affect the rate of flow of water, the creep of loose particles on debris slopes, and if it be permissible to add another factor to the suggested causes of glacier motion we may suppose these vibrations along with those of true seismic origin work in their due proportion woodworth: harvard seismographic station. 21 to the advance of glaciers and icesheets. But no investigation of these possible effects slight as they must be have as yet been under- taken. The daily records of the Station are carefully kept in files awaiting any use which may be made of them for these or other inves- tigations of a like nature. New England Earthquakes. By reason of the frequency and relatively high intensity of seismic shocks in the 17th and 18th cen- turies this region stands undesirably high among the eastern natural provinces of the continent for its seismicity. The catalogues of Brigham and Lancaster include probably nearly all of the shocks which were felt by the inhabitants of New England up to 1870. The fact that neither Brigham nor Lancaster refer to the History of Lynn by Alonzo Lewis in which a few earthquakes are noted not included in their lists makes it reasonable to suppose that the pub- lication in recent years of diaries and personal journals of the colonial period may make known other shocks which have not yet been re- corded in scientific literature. The following additional references to earthquakes are from the 1865 edition of the History of Lynn by Alonzo Lewis and J. R. Newhall. Most of the accounts are also to be found in the edition of 1844 in which Lewis states (p. 17-18) that he has corrected the years and months except when marked in quotations but has left the days untouched. Those earthquakes subscribed "Collins" are given on the authority of a journal kept by Mr. Zaccheus Collins (ed. 1844, p. 6). Additions to the List of Brigham and Lancaster. 1639. On the fourteenth of January there was an earthquake. Loc. cit., p. 182. 1730. Sunday, 12 April, there was an earthquake. Loc. cit., p. 323. 1744. The shock of 3 June mentioned by Brigham and Lancaster is stated on the authority of Collins to have been repeated on the twentieth. Loc. cit., p. 326. 1780. On the twenty-ninth of November there was an earthquake Loc. cit., p. 345. 1805. An earthquake happened on the sixth of April at fifteen after two, in the afternoon. Loc. cit., p. 367. 1814. An earthquake happened on the twenty-eighth of November at twenty past seven in the evening. Loc. cit., p. 377. 1817. There was an earthquake on Sunday, 7th September, and a second on the fifth of October. Loc. cit., p. 380. The first of these shocks is not given by Brigham or Lancaster. 1830. On Wednesday, 1st December, there were two shocks of an earthquake, about eight o'clock in the evening. Loc. cit., p. 396. 22 bulletin: museum of comparative zoology. 1837. On the fifteenth of January at two o'clock in the evening, there was an earthquake. Loc. cit., p. 403. There are a few discrepancies in dates between Brigham's text and that of Lewis. In the case of the shock of September, 1732, given in Brigham's text as on the 15th, Lewis gives the date as the 5th as does Brigham also in his summary table. In the case of the shock dated Sunday, 16 February, 1737, there is some confusion. Lewis gives on the authority of Collins's Journal a shock on Sunday, 6 February, 1737 and mentions none in the year 1736. Brigham also gives a shock for 6 February, 1736. It seems better to regard the dates given by Brigham as referring to a shock the corrected date of which is that given by Lewis. Concerning the legendary fall of rock at Pirate's Dungeon in Lynn in the earthquake of 1658, mentioned in the earlier editions of Lewis's History, see the cautious account of this unsupported statement in Newhall's edition of 1865 (p. 244-250). Bibliography of New England Earthquakes. In this list the writings cited by Brigham and Lancaster are omitted as being readily found from the references which they give. Lewis, Alonzo, and J. R. Newhall. The History of Lynn, Vol. 1, 1865. Vol. 2, by J. R. Newhall, History of Lynn, 1864-1893. Lynn, 1897. Brigham, W. T. Historical Notes on the Earthquakes of New England. 1638-1869. Memoirs Boston Society Natural History, 1871, 2, p. 1-28. Lancaster, A. Note additionelle a Memoire de M. W. T. Brig- ham, intitule "Volcanic manifestations in New England, 1638-1870. Memoirs Boston Society Natural History, 1873, 2, p. 241-247. Perley, Sidney. Historic Storms of New England. Salem, Mass., 1891. Gives accounts, without reference to authorities, of the earthquakes of 1638, 1663, 1727, 1744, 1755. Woodman, J. E. The earthquake of March 21, 1904, in Nova Scotia. Proc. Trans. Nova Scotia Institut. Sci., 1895, 11., p. 227- 235. In the History of Lynn, loc. cit., p. 345, there is mentioned Dr. John Perkins of Lynnfield who died in 1780. He is credited with having published in 1755 a tract on earthquakes. Not seen. The N. Y. Tribune Annual gives many references to New England shocks continuing the lists of Brigham and Lancaster. Ready method of approximate determination of epicentre with data from requisite number of stations. — There are several woodworth: harvard seismographic station. 23 methods varying in precision and in the labor they involve employed in determining the position of epicentres. The method mentioned by Milne of drawing circles on a good globe is the simplest approximate method, but is somewhat awkward to manage and does not leave a record of the process for future reference and revision. At this Station the following method is planned for obtaining an approximate determination. On a Mercator chart of the world for each princi- pal station exchanging data and placed in a suitable position for giving good results meridians are drawn on Lambert's projection passing through the Station and its antipodes thus giving the paths of all ways entering the Station. About the Station and its antipodes curves of equal distance say 100 kms. are drawn representing parallels in Lambert's projection. The distance curves are made the basis of the following operation for determining the position of the epicentre as in the intersection of circles. In a book of blank Mercator maps printed on the same scale as the maps for the several stations but on transparent paper, the Station maps are slipped in succession under the page on which the record is to be made in exact registration and the appropriate circles of distance traced. Their intersection solves the problem as in the use of the globe. The same map in the Register of Epicentres may be employed for marking out several cases, e. g., those of a given month. The argu- ment for Lambert's projection and a drawing which may be enlarged to any given scale of Mercator chart is to be found in Encyclopedia Britannica, 9th edition, 10, p. 208-209. The most expeditious way of determining the position of the curves of equal distance about a station is to draw them with compasses on a slate globe provided with suitable lines of latitude and longitude and to trace the curves through corresponding points upon the Mercator projection. Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vol. LV. No. 2. GEOLOGICAL SERIES, Vol. IX, No. 2. HARVARD SEISMOGRAPHIC STATION FOURTH ANNUAL REPORT FOR THE YEAR, 1 AUGUST, 1911—31 JULY, 1912. By J. B. Woodworth. CAMBRIDGE, MASS., U. S. A.: PRINTED FOR THE MUSEUM. February, 1913. No. 2. — Harvard Seismographio Station. Fourth Annual Report for tin Year, 1 August, 1911—31 July, 1912. By J. B. Woodworth. The seismic records given herewith continue the list published in the Bull. M. C. Z., 55, p. 1-24. The constants of the Station remain as in previous yeais: viz. — Latitude 42° 22' 56" N. Longitude 71° 06' 59" W. Altitude 5.36 M. Time: — Mean Greenwich, midnight to midnight. Instruments: — Two Bosch-Omori 100 kg. horizontal pendulums, with mechanical registration. Period of pendulums, 25 sees. Magnification: — N., 50; E., 80. Damping: — N. 4:1 (See Remarks). E., O. Nomenclature : — Gottingen. In the column of Remarks the following abbreviations are em- ployed:— Q, quake, earthquake; Qf., felt eaithquake; Ql., local shock; Qr., earthquake reported; O., origin or epicentre; TO., time at origin, calculated by Benndorf's tables; A, distance from Cam- bridge to origin, calculated from record. Micros., microseisms mask the record. No. Date Phase Time Peri- Ampli- ods tudes Remarks 1911 Ii. in. s. s. mm. 149 Aug. 16 NP S L 23 00 38 23 19 19 23 38 31 Klotz gives O = 4> 31° 24'N,X142°28'E. Aug. 17 M 0 00 19 Qr. Eap, W. Caroline F 1 16 Ids. 150 Aug. 27 eNP eS eL F 11 08 00 11 12 25 11 21 15 11 49 Klotz gives O = 0 31° 50' N, X 112° 15' W. No maximum. 151 Sept. 6 NP S 1 06 25 1 17 19 E-W component out of order. 28 bulletin: museum of comparative zoology. No. Date Phase Time Peri- ods Ampli- tudes Remarks 1911 eL? F h. m. s. 1 28 59 1 37 54 2 03 s. mm. .6 Klotz gives O = 52° 58' N, X 143° 20' E. Miyako, North Nippon, Japan. A 10,000 kms. 152 Sept. 8 NL F 23 29 00 23 41 22-23 Strassburg A 9320 kins. 153 Sept. 13 NP eL F 3 23 13 3 34 49 4 11 , A 4750 kms. Qf. at Tres Acequias, Bajo Mioyano, Argentina. 154 Sept. 15 P S eL 13 20 22 13 28 42 13 43 03 M 13 45 31 6.5 O near Iquique, Chile. F 14 A 6780 kms. 155 Sept, 17 NP E NS E eNL E 3 36 01 3 36 31 3 48 12 3 49 34 4 04 58 4 05 20 11 Obscured by micro- seisms. Obscured by micro- seisms. Beginning of P very uncertain. Klotz: O = 28° 14' NM 4 09 15 20 N, X 140° 30' E. E 17-22 NM 4 10 58 26 2nd Q in Coda. E 22 NM 4 13 39 27 NF 5 45 06 E 5 27 156 Sept. 20 eNL E eNL E NF E 5 34 53 5 35 12 5 36 28 5 36 02 5 54 5 53 28 28 20-15 20-15 Ottawa eL 5-32.3. woodworth: harvard seismographic station. 29 No Date Phase Time Peri- ods Ampli- tudes Remarks 1911 h. m. s. s. mm. 157 Sept. 20 eNL E NF 5 59 24 6 00 6 01 22 13-16 Probably part of pre- ceding group. 158 Sept. 22 eNP 5 10 05 3-4 Klotz gives O = 60° eE 5 10 02 2 26' N, X 146° 30' W. NS 5 17 00 * 13 Prince William Sound, eNL 5 25 36 24 Alaska. E 5 24 37 NM 5 26 46 5.7 A 5230 kms. (3250 mi.). NF 6 10 14 E 6 14 TO 5h. 03m. 01s. 159 Oct, 6 NP E 10 20 13 10 20 53 6 San Domingo earth- quake. NS 10 24 29 10-17 A 2640 kms. (1630 mi.). E 10 24 41 NL 10 29 53 20 Klotz gives 0 = 0 17° E 10 30 37 44' N, X 71° W. NM 10 32 56 4.7 Tidal wave reported at E? 10 31 24 0.1 Guaymas, Mex. F 11 38 TO lOh. 16m. 19s. (Station clock out of order) . 160 Oct. 10 eEP? 13 18 17 3-4 Masked by micro- seisms. S? 13 23 45 il2 Station clock electric NL 13 26 38 contact out of order and E 13 26 08 22 times very uncertain. NM 13 32 50 7.5 Klotz gives O = 4> 12° E 13 30 13 3.0 02' N, X 84° 36' W. EF 14 31 N drum stopt at 14:26. 161 Oct. 13 NS 2 55 43 2 56 32 6 12 O = 48° 34' N, X 157° 35' E. (Klotz). eL 3 22 20 0.5 Time uncertain by 30 F 4 16 sees. 162* Oct. 14 eN 17 00 35 17 09 39 35-36 36 P lost in micros. Sta- tion clock out of order. 30 bulletin: musel.m of comparative zoology. No. Date 1911 163 164 Oct, 20 Oct, 26 165 Oct. 29 166 167 Nov. Phase Time h. m s. Peri- ods Ampli- tudes Remarks s. mm. L 17 12 30 24-20 Time very uncertain. M 17 15 37 3.0 Reported for record of eE 17 09 44 phases. Ottawa el7-01 -20. L 17 14 54 16-20 (1.0) No decided M. F 17 36 • Lost in micros. eEL 18 44 40 Batavia P 17-53-48. F 19 01 eNP 14 19 32 3 ' No decided M. ?S 14 21 43 11-30 (1.5) Began and ended L 14 31 21 25 masked by micros. EL 14 32 57 28-18 (0.25) Irregular LL? during NF 15 01 forenoon of 26th. eNP 18 19 15 Masked by previous S 18 23 54 18 28 19 10 12 line. eL 18 36 20 17 No maximum. F 19 15 eEP 18 19 01 4 Ottawa P 18-17-18. S 18 23 54 18 27 09 6 12-10 LL not well denned. L 18 35 55 18 39 55 17 14 F 19 12 NP 9 33 38 3 Ottawa P-9-33-50. E 9 33 32 2-3 NS 9 39 12 12 A3770kms. (2375 mi.). NL 9 44 46 24 (0.2) eEL 9 47 08 20 Q reported from San NM 9 48 '26 7.0 Juan del Sur, Nicara- NF 10 34 38 gua (2400 mi). Press gives time 3:40 a. m. TO = 9-27-23. eNS 6 12 44 8 L 6 15 00 9 Microseisms ? woodworth: harvard seismographic station. 31 No. Date Phase Time Peri- ods Ampli- tudes Remarks 1911 M F EL? M F h. m. s. 6 15 02 6 35 6 15 00 6 15 10 6 25 s. 10-12 mm. 0.9 0.5 168 Nov. 13 eN? Earlier phases masked L 16 47 43 25 by microseisms. Bata- F 17 52 via P 16-25-23. E-W record ill defined. 169 Nov. 18 eNS? 7 45 52 7 55 13 8 24 P lost in microseisms. L? 7 56 01 14-18 (0.75) Ottawa P? 7-37-32. C 7 58 41 F 8 31 40? eE 7 46 06 L 7 56 02 20 F Lost about 8-20 in micros. (Nov. 19) (No records between 17hrs.and21hrs.30m.). 170 Nov. 20 eN 14 03 27 P masked by micro- seisms? S 14 06 40 26 Attendant was setting L 14 09 43 up instruments as late M 14 11 20 8.0 as 14h. 03m. lis. F 14 24 38 Masked by micro- seisms. eEP 14 02 23 L 14 08 35 22 Qr. Martinique, W.I. M 14 11 06 20. 8.0 F 15 ? 171 Nov. 21 eP 18 53 47 3-4 S 18 54 36 16 1.0 E-W microseisms only. L 18 55 16 9 0.5 F 19 01 42 32 bulletin: museum of comparative zoology. No. 171a Date 1911 Nov. 22 172* Nov. 25 173 174 175 Dec. 16 Dec. 20 Phase Dec. 22 eN eNL eL? F? eEL L? F? O NP S L M M F EP S L M M F eNS eL F eES L M F eEP S Time ll. Ill- s. 10 28 26 10 29 28 10 34 36 19 51 41 19 51 50 19 56 47 19 52 51 19 53 50 19 56 40 19 14 39 19 21 22 19 27 28 19 34 46 19 37 38 19 39 24 20 34 12 19 21 19 19 27 01 19 35 14 19 37 40 21 51 6 21 13 6 28 23 7 04 6 15 17 6 21 37 6 25 26 6 28 43 7 19 13 01 51 13 07 33 Peri- ods 7-8 20 10 10 6-3 17 14 4-6 10 28 22-25 14 40 20 18 40 20 20 4-5 12-14 Ampli- tudes mm. 1.0 45 40 0.5 Remarks P? and F masked by- micros. St. Louis e 19-35.8. O = SW? Estimated time of earthquake. S-P6m. 6s.A4330kms. 2700 mi. L-S 7m. 18s. Qf. Mexico. O = 0 19° 10' N, X 102° 15' W. (Klotz). Damped pendulum. S-P5m.42s.,A3910kms. 2440 mi. L-S 8m. 13s. Undamped pendulum. N-S damped 4:1. P masked by micros. Undamped. S-P, 5m. 42s. , A 3910 kms., 2420 mi. Undamped pendulum. Local jars superposed. Qr. Mexico City 6.15 a. m. woodworth: harvard seismographic station. 33 No. Date Phase Time Peri- ods Ampli- tudes Remarks 1911 F h. m. s. s. mm. Lost in microseisms. No record on N damped 4:1. 176* Dec. 23 eNS eL F eEP? S L F 21 22 43 21 26 25 21 37 41 21 07 09 21 16 57 21 24 56 21 45 Records tangled E-W and masked by micro- seisms. 176a Dec. 23 1912. NM F 22 07 28 22 07 30 1- Local shock. Ice crack; not felt by persons. 177 Jan. 4 eES L 16 05 39 16 22 27 12 24 Ottawa P? 15-57-14. M 16 25 51 18 2 L-S, A 5400? miles. F 17 44 54 N chronograph not re- cording. 178 Jan. 11 NM F 7 25 52 7 25 55 Local unfelt shock at Station. Crack in ground ice. 179 Jan. 11 NM EM F 10 24 58 10 24 59 10 25 01 Local unfelt shock at Station. E gives pre- ferred reading. 180 Jan. 19 M F 0 00 54 0 00 56 1- 14 sees. Local weak shock. Ice coated ground. 181 Jan. 19 M F 1 08 15 1 08 17 1- 4 sees. Local shock. Ice coated ground. 182 Jan. 21 M 12 15 17 1- 0.5 Local shock. Ice crack. 183 Jan. 26 NM F 4 21 22 4 21 24 1- 0.05 Local shock. Crack in ground ice. Not felt by persons. 34 bulletin: museum of comparative zoology. No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. m. s. s. mm. 184 Jan. 26 M F 4 25 16 4 25 18 1- 0.1 Local shock. Crack in ground ice. Not felt by persons. 185 Jan. 26 M F 10 25 28 10 25 31 1 0.3 do. 186 Jan. 26 M F 10 39 29 10 39 31 1 0.2 do. 187 Jan. 26 M F 11 20 48 11 20 49 1 0.3 do. 188 Jan. 26 M F 11 26 24 11 26 26 1 0.5 do. 189 Jan. 26 M F 11 30 19 11 30 21 1 do. 190 Jan. 31 EL? 11 51 40 11 52 52 10 13 No record N-S by damped pendulum. M 11 53 20 10 0.5 Micros. L 11 55 03 15-12 F 11 56 54 191 Jan. 31 eLN 20 35 M 20 36 56 10 14.0 Damping 4:1. F 21 ca EP? 20 20 03 Micros. S 20 26 47 20 27 06 8 8 A 5040 kms. L 20 35 35 32 Qr. near Valdez, Alaska. M 20 36 40 20 34.5 F 21 33 22 192 Feb. 15 e 18 41 12 eEL 18 44 56 15 Micros, only E-W. F 18 48 Damped 4:1. Not reported from Ot- t awa. woomvoRTii: HARVARD KEISMOGRAPHTr station. 35 No. Date Phase Time Peri- Ampli- ods tudes Remarks 1912 h. in. s. s. mm. 193 Feb. 19 EL 23 00 56 17 Micros. only N-S. e 23 01 02 4 Damped 4:1. L 23 01 06 15 Ottawa e? 23-09-27. F 23 11 27 194 Feb. 22 EL 7 38 29 15-20 QQr. Costa Rica ca. • 7 47 24 20 this time. e 7 55 14 11 F 7 55 54 195 Feb. 22 e 8 43 30 eE 8 46 45 24-13 Possibly connected with F 8 51 36 preceding. L interval lh. 04m. as if set off by S of 194 reflected to epicentre. 196 Mar. 11 eNS 10 35 44 8 P masked by micro- seisms. L 10 38 31 18 LE-SN: 2m. 39s.: a M 10 38 47 17 3.0 1800 kms? (Laska). F 11 04 28 F in micros. eE 10 33 39 P masked by micro- eS? 10 38 04 seisms. L 10 38 23 Pendulum undamped. M 10 38 46 9.5 Cf. Batavia e 10-12. F 11 13 50 Ottawa P 10-30-13. 197 Mar. 11 eEL? 19 09 58 20 No record N-S on F? 19 12 28 damped pendulum. 198 Mar. 11 eES? 19 47 04? Micros. 4s. pd. N-S. only. L 19 59 10 20 Micros, superposed. F 20 16 F later? 199 Mar. 29 EL? 16 10 53 19 Among long period L? 16 17 04 20 waves from 14h. 45m. to 20h. 20m. No record on N-S damped pendulum. 6<0 BULLETIN MUSEUM OF COMPARATIVE ZOOLOGY. No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. in. s. s. mm. 200 Apr. 2 eEL? (F) eL? F? 0 46 51 0 47 43 0 55 17 0 56 01 25-18 17 Microseisms N-S. Among waves 30-50s. L? 0 58 15 19-28 period. F 0 59 31 Not reported elsewhere. 200a Apr. 13 . eEL 19 04 18? | 16-17 Undamped pendulum, L 19 07 08? 22-24 per 22s. F? 19 36 20 200b Apr. 14 eEP? eL F 13 40 43 13 56 14 20 4 13-14 200c Apr. 14 eEL F 23 38 11 23 54 42 20 201 Apr. 15 eES? 16 51 27 12 No record N-S by e 16 53 40 12 damped pendulum. eL 17 09 29 20-24 0.1 F 17 16 22 202 Apr. 17 iNP 3 57 09 2-3 S-P, 6m. 33s. A 4830 S 4 03 42 6-8 kms. eL? 4 08 12 14-20 F 4 30 eEP 3 57 10 2-3 e 4 02 55 11 S 4 03 54 11 L 4 08 54 20-26 0.38 F 4 45 203* Apr. 20 eEL F 2 34 11 2 53 20-24 Not shown N-S by damped pendulum. Ottawa e 2-31. woodworth: harvard seismographic station. 37 No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. m. s. s. mm. 204 May 6 NP 19 07 07 4 S-P, 5m. 40s. A 3870 kms. 2400 mi. S 19 12 48 8 O in southern Iceland. EP 19 07 09? S 19 12 47 11 TO = 19-00-37. eL 19 16 55 Strassburg reports P M 19 20 20 16-19 36.5 19-04-42 Qf. in south- F 20 43 43 ern Iceland. Record partly masked by jars from heavy traffic. 205 May 6 eEL F 23 27 08 23 34 20 23 36 23 22-24 24-28 One of several short groups of LL among longer irregular waves on May 6th to 12th. Not reported elsewhere. 206 May 16 eEP? e 15 01 10 15 02 35 3 S 15 03 21 12 L-S, 7m. 6s., A 5600 eL 15 10 27 22 kms.? F 15 13 N component out of commission for repairs from May 18, 21h. to 21h. 45m. E compo- nent out of commission for repairs May 18 from 21h. 45m. to 22h. 45m. 206a May 21 eE eL F 9 55 34 9 20 59 9 34 52 10 36 30 207* May 23 eEP? 2 44 05 16 P masked by micro- seisms. S 2 51 34 8 Undamped pendulum; eS? 2 59 17 3 03 3 15 16 per 25s. N record faint; both eL? 3 06 15 3 10 27 28 20 obscure. 6b BUL LETIN : MUSEUM OF COMPARATIVE ZOOLOGY. No. Date ■ Phase Time Peri- ods Ampli- t tides Remarks 1912 h ra. s. 3 11 36 3 15 18 3 18 26 s. 67 32 25 mm. Record evidently of Q in Burma: Athens P 2-34-48. Ml 3 22 34 31 22.5 M2 3 24 45 25 28.0 M3 3 29 09 22 27.0 F 4 50 208 May 25 eN 16 29 42 Not recognized E-W. eL 16 37 42 22 Not reported elsewhere. F 16 45 52 209 May 28 eNL F eEL F 13 41 13 48 11 13 42 29 13 57 06 20 24-22 Ithaca, N.Y.eL 13-36. 210 June 3 eN eL F eE eS? 12 39 29 13 08 01 13 45 12 39 53 12 55 40 15 0.5 Strassburg P 12-45-18. eL 13 07 01 22-20 0.5 13h. 21m. changed record. 211 June 7 eE F 4 05 53 4 13 37 9-10 212 June 7 eE F 5 01 14 5 03 57 5 05 08 5 18 41 17 10-8 213 June 7 eE eL F 7 42 02 7 45 27 7 51 20 213a* June 7 Ee F 8 28 8 50 214 June 7 Ee L? 9 12 43 9 20 08 8 10-8 Ottawa M 9-23. woodworth: harvard seismographic station. 39 No. Date Phase Time Peri- ods Ampli- tudes • Remarks 1912 F h. m. s. 9 28 09 9 45 30 s. 10 mm. 215 June 7 P S L F? 10 04 29 10 11 26 10 23 O, Alaska. S-P. 7m. 16s., A 5620 kms. TO 9h. 55m. 08s. F in next record. L lh. 02m. 52s. after L of 214 as if set off by S. of 214 reflected to epicentre. 216 June 7 eE F? 11 02 12 Appears to merge into next group of waves. 217* June 7 eES? S L 12 41 37 12 51 16 12 55 18 13 26 40 9 10 20 0.37 M 13 28 20 18 2.8 M 13 31 45 17 2.2 M 13 37 35 20 2.5 F 14 01 218* June 7 eE S? M F 18 49 17 18 52 57 18 53 50 19 12 219 June 8 eEP S L M F? 7 44 44 7 52 09 8 02 01 8 03 15 32 S-P: 7m. 25s.; A 5790 kms. TO 7h. 35m. 40s. F in next group of waves. 220 June 8 e L? M F 9 13 22 9 16 36 9 18 31 9 18 43 40 bulletin: museum of comparative zoology. No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. m. s. s. mm. 221 June 8 e L F 10 26 05 10 30 07 10 34 30 Interval of lh. 12m. after 220. 222 June 8 e 10 54 30 e at 33m. 20s. after S? 10 59 25 8 e of 221. F 10 25 51 Reflected P of 221 at epicentre? 223 June 9 eN L? C F 17 41 58 17 46 56 17 48 01 18 03 31 16 ' e = L? 224 June 9 eN F 22 05 22 22 13 28 Ottawa M 22-04. 225 June 9 eN F 22 37 23 10 Ottawa M 22-39. 226 June 10 eNP 16 15 24 S-P: 7m. 29s.; A 5850 S 16 22 53 10 kms. or 3650 mi. L 16 32 46 16 33 19 18 16 Time at origin 16h. 06m. M 16 39 07 16 17.7 F 17 57 227 June 12 eNL? e L? F 7 30 13 7 31 41 7 35 51 7 49 13 30 13 228 June 12 iNP RjP? S eL 12 49 56 12 50 57 12 55 13 12 59 41 3 S-P, 5m. 17s.; A 3500 kms. (2175 mi.). T at origin 12h. 45m. 35s. M 13 02 56 22 2.2 F 14 15 229 June 15 eN L F 17 34 48 17 38 37 17 46 58 20 woodworth: harvard seismographic station. 41 No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. m. s. s. mm. 230 June 15 eL F 18 50 41 19 01 40 20 231 June 17 eN eS? L 11 39 58 11 49 15 11 51 33 28 20 P and S uncertain. M? 11 58 28 15 0.5 F 12 30 EP? 11 34 36 S? 11 43 22 9 L 11 51 42 20 M? 11 57 58 0.5 F 12 29 28 232 June 18 eN? S L eE S L F? 12 17 01 12 34 42 12 44 32 12 16 50 12 34 42 12 44 32 14 30 20 20 June 20 N Long period irregular waves from ca 13h. to 16h. 15m. 233 June 28 eN 19 02 43 Irregular motion N-S F 19 10 09 8;15 from ca 13h. June 28 to ca Oh June 29. Micro- seisms E-W. 234 June 29 eNP S eL F? ES L? F? 8 02 21 8 11 24 8 25 53 8 26 48 9 10 8 11 09 8 23 45 8 30 3-4 20 eLE-SN, 12m. 36s., A 8000 kms. 42 bulletin: museum of comparative zoology. No. Date Phase Time Peri- ods Ampli- tudes Remarks 1912 h. m. s. s. mm. 235 July 7 NP S 8 06 27 8 13 29 3,4 i Throw of pendulum N. S-P, 7m. 02s.; 5375 eL 8 19 43 48 kms. M 8 23 13 75 Stylus went off drum iEP 8 06 23 4 and no further record. S 8 13 26 L 8 19 57 50 S-P, 7m. 03s.; 5390 kms. M 8 23 13 20 OS 31 42 32 48 22 75 Stylus off drum. Stylus on again. Stylus off again. Stylus on again. C 35 02 Alaskan earthquake. F 10 13 TO, 7h. 57m. 26s. 236 July 7 eNP ■ S L F 22 51 10 23 03 02 23 08 11 23 22 28 8 13 237 July 8 eN F 3 34 58 3 40 31 3 238 July 8 NP S 22 02 32 22 09 50 8 S-P, 7m. 18s. ; 5665 kms. L 22 18 19 15 Qr. Alaska. M 22 18 35 24 F 23 30 21 EP 22 02 34 S 22 09 44 L 22 19 16 31 M 22 18 31 15 F 23 02 10 238a July 9 eNL F 9 13 39 9 21 Just visible; not shown E-W. Ottawa eL 9- 11.3. 239 July 9 eN F? 17 05 34 07 52 08 19 3-4 8-10 240 July 11 NL F 19 08 40 19 29 00 8-12 woodworth: harvard seismographic station. 43 No. Date Phase Time Peri- ods Ampli- tudes 1 Remarks 240a 1912 July 22 eN F h. m. s. 23 49 01 23 49 31 51 14 57 23 s. 11 8 mm. Masked by micro- seisms Micros, only E-W, pds. 3-4s. 241 July 24 NP S L F eEP S L F? 12 07 51 12 14 41 12 19 51 13 10 ca 12 08 11 12 14 45 12 19 51 12 45 ca 4-5 12 13 8 16 S-P, 6m. 50s.; A, 5150 kms. Qr. Piura, Peru. 242 July 25 July 26 NP? L F 23 28 13 0 08 12 1 04 05 243 July 26 NP? L F 3 09 22 3 33 4 ca 20 244 July 30 e? eL F 21 55 02 22 44 19 23 19 40 20 Ill-defined LL pre- ceded by irregular waves. 245* July 31 eN? L F 9 51 19 10 00 19 10 01 52 Ottawa e9-51-36. The above list where it varies from the monthly mimeographed bulletins issued from the Station is marked by an (*) asterisk, indicat- ing some revision or correction of phase or time, made possible by com- parison with the records from other stations or a rereading of the seismogram. It will be observed in the column of Remarks that the epicentres of a few earthquakes only are determined. A more extensive list of 44 bulletin: museum of comparative zoology. exchanges with foreign stations would in part afford the data for such determinations, but in the case of the later records such information would not ordinarily be available until after the lapse of several months. Dr. Klotz of Ottawa is cited as authority for the location of several epicentres. The epicentres of important earthquakes are published by the International Commission, but this catalogue does not appear until four years or more after the annual report of an observatory should go to press. The following notes supplement last year's records. No. 126. Feb. 18, 1911. Epicentre located by Klotz in L. 41° 24' N; L. 74° E. No. 130. Mar. 11, 1911: agrees well with earthquake reported at Varzin, New Guinea (Vd. Monat. Uebersicht. fur Marz). No. 132. Mar. 20, 1911: appears to be record of earthquake at Mar- maras-Sziget, Hungary (Vd. Monat. Uebersicht). No. 136. Apr. 28, 1911, is put by Klotz in L. 0° 58' N (?) ; L. 53° 20' (?). No. 143. June 1*5, 1911, has been placed in theRiu-Kiu Ids., Japan. No. 145. July 1, 1911, is referred by Klotz to L. 33° 20' N; L. 144° 50' W. in California. No. 146, Julv 4, 1911, a Turkestan earthquake, is laid by Klotz in L. 42° 58' N; L. 75° 50' E. , . The use of the Lambert's projection drawn over a Mercator map of the woild described in last year's report has been employed in the office, where data were available, for the location of epicentres. Mr. Winthrop P. Haynes, Assistant in Geology, prepared such projections for Strassburg, Ottawa, Batavia, Seattle, and redrew that for Cam- bridge. This method, which is confessedly approximate and de- signedly expeditious, requires but three or four minutes to indicate the approximate position of the epicentre and serves to show whether the elements for distance furnished by the several stations accord closely enough to warrant the labor of more refined methods of fixing the epicentre. With good records this method shows the latitude and longitude of the epicentre with an error of one or two degrees of lati- tude and longitude at great distances (10,000 kms. or 6,200 miles). Unfortunately the data from the three stations required to determine epicentres have not been available among our exchanges to apply the scheme for more than a few instances during the year. The fol- lowing example worked out for the Turkestan earthquake of January 1, 1911, shows the position of the epicentre as determined by the approxi- mate Lambert projection method and the more precise but somewhat more laborious graphical method invented by Dr. Klotz of Ottawa. woodworth: harvard seismographic station. 45 By Lambert's projection L. 43° 36' N. L. 76° 24' E. By Klotz's graphic method L. 43° 40' N. L. 78° 20' E. Difference L. 0° 4' L. 1° 56' A comparison with Prince Gallatzin's determination of the same epicentre gives the following: By Prince Gallatzin L. 42° 59' N. L. 78° 00' E. By Lambert's projection L. 43° 36' N. L. 76° 24' E. Difference L. 0° 47' L. 1° 36' The difference in position as determined by Dr. Klotz and Prince Gallatzin is — Position by Dr. Klotz L. 43° 40' N. L. 78° 20' E. " Prince Gallatzin L. 42° 59' N. L. 78° 00' E. Difference L. 0° 41' L. 0° 20' The differences in these respective comparisons are to be looked for in (1) discrepancies in the data employed for estimating the dis- tance to the epicentre, since the data are from different groups of stations in each case : (2) errors in projection incidental to the graphic method ; (3) the geodetic uncertainty as to measurements of distance on the surface of the geoid on different great circles. The Lambert projection is weak in the second of these respects. The above determinations of the epicentre by it are subject to two refinements: — 1, a more accurate drawing of the curves of distance from the recording station upon the mercator map; 2, the use of a larger scale with a consequent closer intersection of the curves from the stations employed in determining the epicentre. Dr. Klotz of the Dominion Astronomical Observatory at Ottawa has prepared a set of stereographic projection tables for determining epicentres in accordance with the method invented by him. These tables include the constants for this station. See Journal of the Royal Astronomical Society of Canada, May-June, 1911, p. 209. Local or New England earthquakes. The daily press reported a slight earth tremor felt in Calais, Maine, at 7 A. M., Eastern Standard Time, on March 20, 1912. Not recorded at this Station. Except for certain local unfelt shocks regarded as due to frost cracks during midwinter, no local shocks were recorded during the year; or, if thev are shown on the records, thev have been taken to be the effect of local traffic jars. The earthquake of March 21, 1894, which was felt in Cambridge 46 bulletin: museum of comparative zoology. and in the region thence to the epicentre in Nova Scotia has been de- scribed by Prof. H. F. Reid in the Bulletin of the Seismological Society of America, 1911, 1, p. 44-47, with isoseismal map. Frost crack jars: — The unusual number of small local shocks in the list, referred to frost cracks, during the months of January and Feb- ruary, 1912, were so far as I am aware unfelt, though they were dis- tinctly recorded on both components of the seismograph, invariably setting out with a sharp maximum of motion which quickly died down. In several instances the exact second of beginning of motion on one of the components was obscured by the quaquaversal oscillation of the stylus, the component being thrust to and fro in the direction of its horizontal axis as well as registering its proper lateral motion. These shocks came at times when the ground was largely covered by a sheet of ice resulting from the thawing and freezing of old snow, and during very cold nights. The night watchman reported booming noises in the courtyard surrounding the Station but none of the sounds noticed by him agreed in time with the shocks listed. Several extended wandering cracks in the frozen ground were at the time traceable on Divinity Avenue and in neighboring portions of the University grounds. Powder explosion: — On Friday, May 24, 1912, there was a powder mill explosion at Acton, Mass., 17.5 miles (28.18 kms.) from the Sta- tion, recorded on the seismograph at 6h. 52m. 54s. p. M., (75th meridian time west). The vibrations lasted 4 sees, on the E-W component, whose steady mass was thrown relatively to the west or towards the origin of the disturbance as if the ground were thrust away from the origin. The exact time of the explosion could not be ascertained by correspondence with the officers of the company, so that nothing has been ascertained concerning the speed of propagation of the shock. Lacunae in the records: — The north component was out of commis- sion for repairs from 21h. to 21h. 45m. on May 18, 1912, and the east component was dismantled on the same day from 21h. 46m. to 22h. 45m. Again in June, 1912, the north component was out of commission for repairs on the regulator from 13h. 14m. on the 6th to 20h. on the 8th: the east component was not in use for the same reason from 15h. on the 10th to 2h. 35m. on the 14th, G. M. T., midnight to midnight. Number of Earthquakes recorded since Jan. 1, 1910. Year. Jan. Feb. Mar. Apr. May. Jun. Jul. Aug. Sept. Oct. Nov. Dec. 1910 5 2 5 5 12 9 8 4 10 3 11 12 1911 8 11 356 6 32 87 8 5 1912 3 4477 25 13— — — — WOOD WORTH : HARVARD SEISMOGRAPHIC STATION. 47 The above table includes only the records of distant quakes or felt local shocks. With regard to the general character of the records made out during the year, they may be classified with reference to the phases (P, S, L, M) which they clearly exhibit as follows: PSLM 20%. PSL, 14%. PS, 1%. PL, 4%. SLM, 2%. SL, eL, 10%. LM, 1%. L, 29%. eF, 10%. Local (frost crack) records, 9%. The failure to recognize P, S, and possibly M in certain records has been due to microseisms and other local disturbances. The eF records are short disturbances of no regular period and are not well understood, though their seismic nature is frequently shown by their appearance at other stations at some distance, as at Ottawa and Ithaca, N. Y. If we combine those records containing the beginnings of P, S, and L and consider them good, only about 34% of the records for the year are entitled to this description. Eliminating the frost cracks from the count, this number becomes 37% of the total readings. The reexamination of the records in the light of a knowledge of the times of occurrence of every earthquake registered at other stations would undoubtedly lead to the identification of scores of "irregular" vibrations, and "thickenings of the line" with the passage through Cambridge of one or another of the several phases of distant shocks. Additions and alterations in equipment: — -Through the generosity of Mr. Edward Wigglesworth funds were provided during the year for the purchase of a Wiechert seismographic clock, manufactured by Spindler and Hoyer of Gottingen. The electric contacts of this clock are on the outer face of the dial where they may be readily adjusted. The minute contact lasts one second; and the hour contact, adjustable to several seconds, is conveniently made to take 8 or 11 seconds as desired. So far, the contacts have worked perfectly. This clock is used as the standard station clock, while the old clock, whose elec- tric contact for minutes is not reliable, is kept running and ready to be switched into service when needed. The piano wire turnkey attachments of the guy wires of the booms of the pendulums of the tromometer, which were loosened in 1908 in overhauling the instrument and which could not since then be made to hold the wTires taut, were replaced during the year by turn buckles of bronze and nickle-steel permitting a permanent adjustment of the attachment to any desired tension. A new set of indicators and sty- luses were purchased of Bosch Bios, to replace the original levers which had become deranged by accidents incident to the daily setting up of the instrument. It was discovered that the yoke of the north- south component had been placed upon the pier in a reversed position, 48 bulletin: museum of comparative zoology. preventing the lengthening of the boom to the full magnification of 100 or more times. This error should be corrected; but to do so will require the breaking down of the small concrete tablet on which the yoke stands and the construction of a new one. Damping the tromometer: — As stated by the manufacturers, the 100 kg. tromometer works best when adjusted to a period of 25 seconds. So far the attempt to damp the east-west component with the air damping device has failed to produce the desired results. The pendu- lum fails to respond to seismic vibrations when the damper is attached. The period of the pendulum was reduced to 12 seconds with no better results. Better results have been obtained in the attempt to damp the north-south component. With the heavy diurnal tilt at this Station whereby the pendulums are thrown first to one side and then to other of the zero line, the horizontal pendulum is most of the time pulling or pushing the damper in such a manner as evidently to inter- fere with the free registration of the amplitude of motion of the instru- ment when actuated by seismic waves. Setting the time tickers: — The inherent difficulty in the Bosch-Omori tromometer of setting the time tickers on the drum so as to give an interval of 60 seconds (15 mm.) between the minute mark and the sty- lus at the minute interval has, during the year, been successfully dealt with by swinging the stylus across the line of ticks and depressing the ticker at the instant of transit. Any variation in the space thus marked off from 60 seconds is measured in terms of seconds and ap- plied to that iecord sheet as a correction for time. It is sufficient to blow against the clevis holding the stylus to produce the desired motion of the indicator. In passing from this statement of the condition of the Station, it should be stated that many seismological observatories in this coun- try are now equipped with two or more types of seismographs for recording horizontal motion and that in the vertical; and that the International Bureau recommends that every recording station should be provided with at least two types of seismograph. At present we have one instrument and this requires improvement as regards the damping device since at present our records are defective in not giving amplitudes free from resonance in the pendulums. This particular disqualification can probably be remedied through the purchase of an electric damping device to replace the air dampers now in part use. Microseisms: — The microseisms of November 25, 1911, were partic- ularly well defined and regular. During the maximum, these vibra- woodworth: harvard seismographic station. 49 tions attained a period of six seconds. According to press reports, a furious gale prevailed over the coast of Newfoundland at the time of maximum microseismic vibration at this Station. Macroseisms of irregular period: — During certain morning hours one or both components of the undamped pendulums have given more or less interlaced records having no regular but usually long periods ranging up to one minute, and this at times when no local winds were blowing, though such may have been the case over Massachusetts Bay. At times this motion has assumed a sinusoidal character indi- cating the passage of long or Rayleigh waves from a distant earthquake also registered at other stations. It has been assumed that such irregular disturbances were due to local causes of a nonseismic nature, and no account has been taken of them. Diurnal ivave: — During the month of July, 1912, both components of the seismograph were allowed to swing without damping, thus giv- ing a good record of the " diurnal wave." The plotting of the depar- ture of the stylus from the zero line (line of ticks on the seismogram) for each hour brought out the occurrence of a tilt from north-east to south-west and vice versa. The tilt towards the southwest sets in about 1 p. M. and attains its maximum about 7 A. M., when the tilt to the northeast begins and continues until about 1 p. M. This diurnal wave is superposed upon a longer period swinging of the pen- dulums corresponding with the passage of highs and lows of baro- metric pressure. These graphs are useful in determining the time of day at which the pendulums cross their respective mean positions and thus the hour at which they should be brought to the zero line if they have become placed too much to one side or the other. At this Station for July these hours would appear to be about 8.30 A. M. for the north-south component, and about 9 A. M. for the east-west com- ponent. As, however, the passage of highs and lows, cause the pendu- lums to wander across the theoretical zero line after an interval of several days, such adjustments should be made only when the pendu- lums are crossing the line in one of their long period phases. If the theory be correct that "lows" cause a broad doming up of the earth and "highs" a corresponding saucer-shaped depression, such adjust- ments should only be made at times when the centre of a high or low is over the station, for then only would the pier be level and a proper adjustment to the vertical be made, so as to secure a balanced elonga- tion of the long period swing about the zero lines of the two rectangu- lar components. Earthquake investigations: — Seismology is a subject calling for the 50 bulletin: museum of comparative zoology. special knowledge of the physicist, the meteorologist, the astronomer, and the geologist, and each of these specialists best promotes the science by applying his talents to the development of his phase of the problems which earthquakes present. The study of the seismographic records of distant earthquakes concerns the physicist. The examina- tion of the epicentral tract of an earthquake affords the geologist his opportunity for contributing to the subject as does also the survey of the geological structure of a region with reference to the occurrence and distribution of faults and rock areas liable to affect the intensity of shocks at the surface of theearth. The fact abundantly illustrated in the San Francisco earthquake of 1906 that a fault zone of geologi- cally recent date may at any time undergo renewed motion giving rise to an earthquake makes it desirable in the interests of humanity to locate on maps such lines of danger and point out their existence for the avoidance of unnecessary risks such as arise from ignorance in the choice of location of important public works or private build- ings. Although Boston and vicinity experienced in colonial times earth- quakes strong enough to throw down chimneys and the end walls of brick buildings, no evidence has been found to show that the seismic motion arose from an initial motion of the rocks along any one of the numerous faults and thrust-planes now known to intersect the region. Nevertheless, it seems to be desirable to construct a map of the Metro- politan District portraying the character of the ground with reference to its seismicity or liability to damage in case of earthquake motion. With this end in view some of the research work of advanced students in the Department of Geology has been turned to account. Mr. W. G. Foye was occupied in the fall of 1912 in mapping and studying the fault along the northern border of the Boston basin. The project involves plotting all the faults in the district, classified with reference to their relative geological age, direction of the movements upon them, and with regard to their visible and inferred extension. Upon the same map the superficial deposits having various degrees of stability, such as the glacial deposits and the areas of made-ground bordering the harbor and the Back Bay section of Boston and Cambridge, may be delineated. The importance of engineers and architects taking into account the liability of earthquake shock strong enough to damage buildings in this district is amply shown by the history of earthquakes at Ply- mouth, Newburyport, and Boston in the 17th and 18th centuries. There can be little doubt that the recurrence of such shocks as were woodworth: harvard seismographic station. 51 felt in Boston in 1755 would produce much damage. While the Atlantic coast of the continent is relatively immune from earthquakes, the case of Charleston in 1886 enforces attention upon the necessity of recognizing the risk of destructive shocks upon this] coast at long intervals perhaps of a few centuries only. Sane precaution demands the avoidance of the mistake made at San Francisco of placing a pub- lic reservoir upon a fault zone of recent movement, and of the folly of cheap mortar and rubbly masonry which together were factors of first importance in the loss of life and property in Charleston in 1886, and in Messina in 1908. We may not be able to avoid building our houses and public edifices upon ground liable to destructive shocks, but we have abundant information as to how these structures should be built in order to reduce the risks of demolition to a minimum. Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vol. LV. No. 3. GEOLOGICAL SERIES. Vol. IX, No. 3. HARVARD SEISMOGRAPHIC STATION. FIFTH ANNUAL REPORT INCLUDING RECORDS, 1 AUGUST, 1912-31 DECEMBER, 1913. By J. B. Woodworth. CAMBRIDGE, MASS., U. S. A.: PRINTED FOR THE MUSEUM. October. 1914. No. 3. — Harvard Seismographic Station. Fifth Annual Report, in- cluding records from 1 August, 1912 to 31 December, 1913, G. M. T. By J. B. Woodworth. C. Z. These records are a continuation of the list given in Bull. M. 55, p. 22-52. The constants of the Station are as follows: — Latitude 42° 22' 36" N. Longitude 71° 06' 59" W. Altitude 5.36 M. Subsoil: — -Glacial sand over clay. Time: — Mean Greenwich, midnight to midnight. Eye and ear compari- son with Harvard Observatory through telephone. Instruments: — Two Bosoh-Ornori 100 kg. horizontal pendulums, with mechanical registration. Nomenclature : — Gottingen. In the column of Remarks the following peculiar abbreviations are employed: — Q, Earthquake; Qf., felt earthquake; Ql., local earth- quake; Qr., earthquake reported by press: O, origin, or epicentre, or time at origin when followed by time calculated by Benndorf 's table. Distance in kms. indicates distance from Cambridge to origin calcu- lated from Zeppelin and Zeissig's tables for S-P. Micros., Micro- seisms masked the phases. Constants of the Instruments. VS. E-W. sees. sees. 25 23 50 80 4:1 0. Period : Magnification Damping This report covers the period of a year and a half, bringing the data to the end of 1913. This has been done in order to publish the seismic registrations for a calendar year in a single list instead of dividing the matter as heretofore into lists corresponding with the fiscal year of the Museum of Comparative Zoology (1 August- July 31). No. Date Phase Time Periods Ampli- tudes Remarks 246 1912 Aug. 2 NeL F h. m. s. 20 25 30? 20 41 30 s. 15-20 mm. Doubtful record. Not reported from other Stations. 5G bulletin: museum of comparative zoology. No. 247 248 *249 Date 1912 Aug. 6 17 "250 251 252 18 21 23 Phase Ne? eL? F N P S eL M EeP N eS? L F Ne L? F EeP L? Ne? eL F? Ne? L F Time Periods Ampli- tudes h. m. s. 21 40 00 23 09 1 40 16 1 49 24 2 00 05 2 06 40 11 48 13 07 4 45 19 32 21 19 33 20 19 38 29 19 41 41 20 18 35 20 19 26 22 09 30 15 3 10-8 35 3 8 11 33 35 21 25 08 21 29 51 21 44 21 26 41 21 29 25 18 36 17 19 07 40 14 53 21 15 53 3 8 28 20 24 mm. 19.5 12.5 14.0 Remarks Cf . Strassburg e 21-30- 20. Near New Hebrides. Qf in the Dardenelles, European Turkey. O lh-29-13. 7765 kms. SE-PN, 9m 20s, 8000 kms. Several groups of LL gradually increasing to maximum. E-W component re- strained by faulty ad- justment. Q Eastern Mindinao, Philippines. Qr near Williams Ari- zona, from 2:05 to 2:10 p. m. in 105th M. W. time. Jena O, 21h- 9m-26s. Irregular motion pre- ceded record. Cf. Ba- tavia & Pare St. Maur. In Borneo (Jena). Qr Peshawar, N. W. India. Cf. Strassburg P. 14-14-18. woodworth: harvard seismographic station. 57 No. Date Phase Time Periods Ampli- tudes Remarks 1912 h. m. s. s. mm. 253 Aug. 31 N L F 23 04 23 29 13-17 No trace E-W. Cf. Strassburg P 22-35.5. O in Kamtschatka (Graz). Cf . Guadalajara, Mex. N.B. The Seismograph of this Station was out of commission from Sunday, Aug. 25th ca 15hrs. G. M.T. to Mon- day, Aug. 26th, 13h. 38m. G. M. T. 254 Sept. 1 NeS? 4 43 8 Ottawa P 4-34-26; 54. L? 4 46 20 (0 = 4-27-31). F 5 14 E-W: short group of LL only. Batavia reported Q dis- tant 4510 kms P 4-17- 14. Samoa (Jena). 255 3 Ne F 18 35 36 18 40 50 6-8 Like microseisms. Ottawa e 18-33-09. Ee 18 35 22 5-7 Ithaca-Cornell e 18-33- F? 18 40 37 30. 255a 10 Ne? F? 16 20 06 16 23 32 3 Records begin and end in microseisms. Cf . Ot- Ee? 16 19 43 16 20 18 3-4 6 tawa. L? 16 22 51 12 F? 16 31 24 256 13 NeP? 23 42 13 4 eLE-ePN? 7,800 kms. 14 eL? F? 0 05 34 0 25 24 Qr Rodosto, Vilayet of Adrianople. 13 EeP? 23 42 21 4 0.3 N damped 3:1. 14 eL F 0 03 30 8 ca 20 E damped 0. 58 bulletin: museum of comparative zoology. No. Date 257 *258 259 260 261 262 1912 Sept. 20 29 Oct. 12 Oct, 18 Phase 31 31 Ee? F? Ne? eL? F EeP? eS? eL? Ne?L F E e?L F NeL F EeS L M F Ee eL F EeL F? Time h. m. s. 21 48 43 21 52 47 22 57 57 21 40 35 21 50 35 22 33 15 21 10 20 21 28 35 21 48 13 21 50 17 22 54 15 57 16 35 16 03 16 38 12 30 03 12 54 41 12 21 40 12 29 09 12 31 19 13 25 ? 12 27 17 12 32 35 12 55 15 IS 21 00 19 21 Periods Ampli- tudes s. 3-6 10 6 22 3 7 30 24 18 25-20 6 18 6-12 16 Remarks e in micros. Ottawa e 21-41-11. Tacabayu P 21-11-48; F. in mi- cros. e-F in micros 3-4s pd. Qf Mariana Ids. Pacific Ocean. 13,300 kms. from Cambridge. Ottawa S, 21-21-18. 16-02 to 16-08- chang- ing record. Microseisms. 15-55 to 16-02 chang- ing record. Ottawa P 15-40-26. Qf Aleutian Ids. Qf Aleutian Ids. Distance 5850 kms. StrassburgP 12-20.9. O, Azores. I Qf Philippine Ids. i Irregular pulsations for ! several hours before and after. woodworth: harvard seismographic station. 59 No. Date Phase Time Periods Ampli- tudes Remarks 1912 h. m. s. s. mm. 263 Nov. 7 N P 7 49 23 2-3 Cf. Qr. Seward, Alaska S 7 56 43 6 10 P. M. eL? 8 08 19 15 M 8 08 44 16 1.3 Damped 4:1. F? 3 15 E P 7 49 23 3 Distance 5700 kms. S 7 56 53 6 L? 8 08 02 22 M 8 08 26 20 Undamped pendulum. F 9 27 ca 264 7 Ne? L F? EeS? eL 17 02 41 16 56 50 17 04 45 LN-eS?E = 5m Is = 4700 kms? Vd. Ottawa. 265 7 NeL 17 46 36 Damped 4:1. EeL 17 48 24 27 Undamped. M 17 51 15.6 Vd. Ottawa. 265a 17 NeS? 11 49 47 Damped 4:1 and so in eL? 11 52 35 20 December. L 11 52 59 F 11 57 37 EeS 11 45 29 Undamped and so in eL 11 52 45 20 December. F 12 14 29 Distance 5300? kms. *266 19 EeP? 13 58 25 3 eS?-eP? equals 6m eS? 13 06 25 6 equals 4225 kms. Qr eL? 13 10 35 40 at Acambay, Mexico. N-S micros only. F? 14 18 O 13h 52m. 267 Nov. 27 NeS? 9 37 27 Micros. EiS 9 37 13 12 0.5 i throw to W. eL? 9 38 28 13 F 9 49 47 *268 Dec. 5 j NeS 12 43 53 4 Qf Alaska. 60 bulletin: museum of comparative zoology. No. Date Phase Time Periods Ampli- tudes Remarks 1912 L eL? F? h. m. s. 12 51 15 12 56 08 13 28 s. 10 6-7 mm. F lost? Began to change records 13-28- 13. EeP? 12 36 14 4-2 Micros? eS 12 42 32 eL 12 48 10 10 Dist.4560?kms. L 12 58 38 16 F lost. 269 Dec. 5 Ee? EL F? 15 00 32 15 01 37 15 07 04 N-S faint. Irregular periods before and after. Wind effect? No re- reports. 270 5 NeL F EeS? eL F 18 07 19 18 07 37 18 17 05 18 04 22 18 07 17 18 07 33 18 23 ca 18 16 20-15 14 Cf. Ottawa P ? 17-59- 09. 271 7 NeP 22 57 04 Dist.6450kms. iS 23 05 38 8 i throw N. L 23 09 04 0 in S. Atlantic? F 23 22 05 EiS 23 05 12 i throw E. L 23 09 32 iS very strong. F 23 28 24 272 9 NeL F? Ee? eL F 0 40 46 0 49 52 0 31 52 0 40 32 0 56 36 e masked by micros. Cf. Besancon PO-01-44. O in Japan. (Graz). No maximum. 273 9 NeP? e 8 37 22 8 38 35 In microseisms. s. 8 43 13 8 Dist.3600kms. woodworth: harvard seismographic station. 61 No. Date 1912 274 Dec. 12 275 276 22 23 Phase 277 24 277a 1913 Jan. 1 NeL M F E S? eL M Ee L F? Ee Ee L F EeP ? L F Ne F Ee F Time h. m. s. 8 46 39 8 52 11 8 54 16 9 49 ca 8 42 46 8 45 42 8 51 40 8 53 34 8 54 44 9 55 ca 12 05 52 12 16 44 23 45 03 23 46 23 23 51 03 12 44 51 12 47 57 12 58 37 0 19 21 0 35 36 1 03 48 1 57 ca 18 32 57 18 35 43 18 31 37 18 35 16 Periods Ampli- tildes 15 6 22 25 20 18 52 20 16 65 20 3 27 20 mm. 4.5 14 17.5 25 Remarks Off Central America? Damped 4:1. e lost in micros, and wind-quavers. Undamped pendulum. Faint record of doubt- ful character. Unheard from. N-S chronograph ran down at 17h-32m, Dec. 12. E-W stopt between llh. 19m. and 13 h. 13m Dec. 13th. Cf Ottawa 23-42-21. F? later? in micros. N-S not recording. Faint record of doubt- ful character. Unheard from elsewhere. Record taken off at 13h 20m. Faint. Not shown N-S on pendulum damped 4:1. Vd. Batavia & Strass- burg. O. in Philippines. Qr. in S. W. Union Co., So. Carolina. Vd. Bull. Seism, soc. Amer., 3, 6-13. Time at O reported lh 27m E. S. T. 62 bulletin: museum of comparative zoology. No. Date Phase Time Periods Ampli- tudes Remarks 1913 h. m. s. s. mm. 278 Jan. 7 8 Ee eL F 23 52 17 23 52 25 0 05 15 Cf . Manila P 22-53-33. *279 11 EeL F 13 55 39 16 03 Cf. Manila P 13-20. 280 15 NP PRi S L F EP PRi S L 18 58 56 19 00 16 19 04 26 19 13 20 19 28 18 59 00 19 00 18 19 04 28 19 12 57 Distance 3700 kms. O near X 100° W, 17° 33' N.? Cf. Manila e 19-11. F 20 07 281 19 NEL 18 16 30 D 13,900? kms. F 18 50 O?nearX12O°E028'N. EeS 17 43 54 by Harvard, Ottawa & L 18 12 18 Strassburg. F 18 52 ca 282 19 NeL F 19 12 14 19 13 28 Cf. Graz L19h., 28m. Falls within Record 281 at Ottawa, W1 ? If so, A = 13,300 kms? 283 22. Ee? F 18 30 06 18 35 34 var. ' Pulsations? Unheard from. 284 23 Ee F 12 29 07 12 32 var. Cf. Ithaca, N. Y. e? 12-09; F 14:01. 285 23 NeS? 14 45 12 6 Cf. Sydney eP 13-59.3 eL 15 05 02 20 0 . 1 D. 5800? kms. (Sydney) F 15 51 47 Ottawa e L 14-55.5. EeS? 14 46 31 8 L 15 04 37 20-25 0.15 F 15 51 48 WOODWORTH: HARVARD SEISMOGRAPIIIC STATION. 63 No. Date 286 287 288 289 289a 290 291 1913 Jan. 31 Feb. 9 27 Feb. 20 23 Mar. 3 Phase Time NeP PRi S eL? F EeL EeS? eL F Ee? eL F EeS? L F EeS? M F Ne 291a 292 F 4 ES? L F 8 EeL F S EeP S eL h. m. s. 22 54 52 22 56 09 23 00 46 23 10 21 23 30 ca 23 08 45 8 23 02 8 29 20 8 32 ca 20 56 36 20 59 48 21 08 41 9 22 53 9 41 54 10 23 3 08 21 3 22 27 3 29 ca 3 27 41 3 29 14 Periods Ampli- tudes 11 40 21 11 42 4(1 11 44 43 11 59 25 15 31 18 15 35 31 15 59 46 16 04 59 16 07 14 10 8 28-24 9-8 6 IS 20 24-12 o 26 mm. Remarks 0.16 D. 4120 kms. Ottawa A 4220 kms. Cornell A 4220 kms. O = 22h. 47m. 34s. O, near 100 W, 16 N. Doubtful record. Not reported elsewhere. Hour doubtful, heard from. Not Dist. 10,600 kms.? Ja- pan? O = 8h. 57m. 08s. Qr. Guayaquil, Ecuador P & S masked by mi- croseisms. Among microseisms of 3 to 4 sees, period. E record in tangled lines of undamped pen- dulum. L-S? 4m. 34s.: 4500? kms. 0.15 Micros. N-S damped 4:1. Very faint. Not hoard from. Undamped. kms. D 3440 64 bulletin: museum of comparative zoology. No. Date Phase Time Periods Ampli- tudes Remarks 1913 h. m. s. s. mm. M? 16 09 56 27 2.2 Qr. Guajiniquilapa, F 16 46 30 Guatemala ca 90° 17' Ee 16 52 31 W. ca 14° 12' N. L. F? 16 56 09 Vd. Bull. Seism, soc. Amer., 3, p. 35. 292a Mar. 9 L F? 16 23 40 16 34 20 Faint LL N-S; masked by microseisms. 293 10 EeL F 14 45 41 15 05 03 18-20 ' Very flat waves. Micros. N-S 3.51s pd. (Cf. Sydney, N. S. W., M. 14-08-21). *294-5 14 NP L 9 04 19 9 07 12 9 08 22 9 08 38 9 09 27 9 12 02 9 12 05 9 23 59 9 42 44 2-3 3 6 4-3 3-6 P. pds. in groups. Qr. Sanger Id. Eastern Mindinao, <*> 3° 30' N. X125°30'E. EP 9 04 21 9 05 00 9 05 55 9 06 35 9 09 47 9 12 19 2 6 2-4 8-10 6-8 E-W undamped comp. 9 23 54 35 20 Excessive motion of un- L 9 42 44 damped pendulum. i M 9 50 10 throw E. L 9 53 44 26-20 Sinusoidals set in. 10 21 44 100 2 LL100>70>46>40s. 10 26 35 15 Sinusoidals repeated. (F) 11 23 30 L 11 24 14 36-40 F 11 29 12 296 15 NP 22 37 41 4 Distance 1750? kms. woodworth: harvard seismographic station. 65 No. Date 1913 297 298 Mar. 17 31 299 299a 299b 300 31 Apr. 13 25 Phase L? F EeP eL? F EeS? L? F NP S L M F EP S L M eL F EL F E Ne L M F EeP S eL F Time Periods Ampli- tudes Remarks s. 18 h. m. 22 41 22 47 22 38 16 22 41 50 22 48 ca. 13 55 54 13 59 48 14 19 30 51 40 02 04 16 15 19 42 23 15 47 ca 51 43 00 53 16 01 19 59 24 21 6 49 7 35 12 7 48 7 36 26 7 43 49 18 55 19 03 52 19 10 41 19 38 18 18 37 18 34 37 19 01 34 20 36 6 4 20-13 2 20 3-4 8 24 20 5-4 10 20 0.5 0.75 12.5 7.5 vd. Ottawa, Ithaca (Cornell). Not reported elsewhere. Wind effects? Dist. 7865 kms. O, 3h. 40m. 30s. O near X 180° W; 0 ca. 49° N. From epicentre of 298? Cf . Ottawa e 6-59. O in So. Japan? Tangled record, Vd. Ottawa e 10-41-12. Cornell e 11-25-30. Qr. Mindanao. 66 bulletin: museum of comparative zoology. No. Date Phase Time Periods Ampli- tudes Remarks 1913 h. m. s. s. mm. 301 Apr. 29 NP 0 30 03 0.4 Dist. 435 kms. M 0 30 53 0.5 .7 Qf . St. Lawrence Valley F 0 33 34 south of Ottawa. EP 0 30 02 M 0 30 50 .8 O = Oh 29 m. 7s. F 0 33 34 302 Apr. 30 NeL M F EeL F 0 06 59 0 12 20 0 16 21 0 06 43 0 31 40 20 20 Vd. Ottawa & Graz. O in East. Hemisph. 303 30 NeL F 12 11 31 12 18 49 16 EeS 11 53 48 8 5250 kms. plus. L 12 06 01 25 F 12 55 304 May 8 EeP ?PPm s eL F 18 54 00 18 55 05 19 01 30 19 03 34 19 09 32 19 16 29 19 34 50 20 10 ca 10 06 20 24 18 • Very faint LL. N-S damped 4:1. 5890 kms. 305 16 Ne F 12 13 42 12 15 45 12 30 44 3 6 Cf. Ottawa PI 1-53-39. 306 18 NeL F Ee? 3 08 19 3 17 06 2 59 47 24 Very faint NS micros. 3^lspd. L? 3 02 56 24 eEW in tangled lines. L 3 08 07 3 11 31 20 20 F 3 43 307 24 EeL L 8 00 07 8 15 45 18 woodworth: harvard seismographic station. No. 308 Date Phase 1913 Mav 30 309 June 4 310 311 312 313 314 14 14 14 NeL F EeP? S eL M L EeL EeL M F? EL F EeP S? eL? F EP S L M F eP? S L F Time h. m. s. 12 24 58 12 39 58 12 59 5G 13 25 12 09 32 12 18 12 12 37 42 12 42 30 12 52 33 13 00 21 14 08 30 10 52 09 10 58 47 11 03 47 12 06 ca 10 46 18 10 52 07 11 36 13 11 48 ca 8 43 40 8 49 02 8 56 07 9 31 47 Periods Ampli- tudes Remarks 25 42 20 2 6 38 20 16 20 36 24 20 20 20 2 6 22 0.9 9 44 06 2 9 53 08 10 04 30 10 10 11 29 11 38 33 3 11 43 32 9 11 47 24 20 12 ca Micros, mask P and S. Sydney, N. S. W. re- ports "S. of New Po- merania? ' ' Masked by microseisms. Sinusoidal waves. Undamped pendulum. Merges into next? Possibly 310 & 311 one record. Not traceable on N-S damped com- ponent. S-P : 3580 kms. S— P:7635 kms. Qf Trnova, Bulgaria. Graz O = 4> 42° 13' N. X 26° 17° E. Micros, only N-S on damped comp. S-P: 3230? kms. 68 bulletin: museum of comparative zoology. No. 315 Date 1913 June 22 Phase "316 June 26 Time 317 318 NP S L? F? EP S L M F NePR S eL? F EeP? P ePPu? S h. m. s. 14 01 06 14 10 43 14 23 23 14 28 14 01 11 14 10 11 14 25 44 14 28 33 15 41 29 July 7 M C F Ee L? F Ee? 16 24 32 39 44 46 49 49 51 15 11 12 16 23 25 32 50 52 54 56 57 57 13 54 37 07 44 31 43 01 49 27 ca 46 12 52 05 23 53 33 47 20 56 04 36 ca Periods 15 40 15 42 34 15 49 17 47 44 3 11 20 54 35 16 14 26 7 11 20 30 28 30 22 22 22 24 11 Ampli- tudes mm. i5E 38E 37W Remarks SE-PN 9m. 5s. 7700 kms. Changed records. Undamped pendulum. Damped 4:1. Micro- seisms. See note p. 75. Qf. Samoa & Tonga Ids. Damped amplitudes very small. Undamped pendulum. Looks like iS. Sinusoidals — well- formed. Doubtful record, wind? Undamped pendulum. woodworth: harvard seismographic station. 69 No. Date Phase Time Periods Ampli- tudes Remarks 1913 eL? F h. m. s. 18 30 42 18 41 19 19 16 09 19 53 s. 30 20 16 mm. 319 July 8 EeP? S? F 8 54 8 56 9 04 3 6 320 8 EeL F 22 03 10 04 00 22 35 oa 28 20 Lost in wind waves of long periods. 321 9 Ne S? F Ee? S L? F 0 26 25 0 26 40 0 39 0 22 14 0 24 10 0 25 17 0 58 3 6 Damped 4:1. Undamped pendulum. 322 9 EeL F 12 47 19 12 54 10 323 12 EeL F 10 56 09 12 ca Vd. Czernowitz e P 10- 36-48. *324 22 EP? S? L? F 6 46 04 6 54 04 6 59 55 Recorded in tangled lines. Ottawa record differs. 325 24 EP? S eL F 9 04 28 9 09 46 9 11 07 9 23 8 16 3550 ? kms. Vd. Ottawa. « 326 25 Present, but in tangled lines. Ottawa P 12-44- 46. 70 bulletin: museum of comparative zoology No. Date Phase Time Periods Ampli- tudes Remarks 1913 fa., m. s. s. mm. 327 July 26 EP? 20 58 29 S 21 04 24 6 4140 kms. O 20h. 51m. L 21 11 09 47s. F? 21 45 O in Roumania X 27° 10'E.4>40°37' N. *328 28 EP? S L 5 49 36 5 57 35 6 07 19 6430 kms. O, 5h. 39m. 42s. O.S.Amer.? - F 7 03 329 Aug. 1 EeP S L F 17 23 24 17 33 25 17 48 55 18 59 8090 kms. Vd. Pola Record. O, 17h. 11m. 04s. O in S. Atlantic? 330 5 EeS? 2 05 6 Doubtful record. Not NL 2 16 16 heard from. EF 2 52 331 6 NP 22 24 30 4 6520 kms. S 22 32 34 8 O: 22h. 14m. 50s. L 22 46 18 22 M 22 49 19 25 1.25 Damped 4:1. F 23 49 16 Qr Caraveli and Qui- EP 22 24 36 cacha, Peru. S 22 32 36 L 22 42 12 M 22 50 51 F? 332 7 EeP? L F 2 16 36 2 39 36 3 22 3-4 20 Not heard from. *333 13 NP EL NL NF 4 44 19 5 15 58 5 42 (i 33 Straits of Sunda (Ba- tavia) . woodworth: harvard seismographic station. 71 No. Date ■ Phase Time Periods Ampli- tudes Remarks 1913 h. m. s. s. mm. 334 Aug. 15 EP? 19 27 24 4 Undamped pendulum. S? 19 35 00 8 Dist. 6000 kms? L 19 46 59 28 19 54 34 20 0.25 Pulkovo gives 26.9° N, F 20 39 19 141.5° E. 335 17 Ee L F 17 59 53 18 04 08 18 09 43 6 10 Ottawa L 18-04-30. 336 31 Ee 18 01 01 10 L 18 07 34 26 Ottawa eL 18-07. F? 18 48 *337 Sept. 3 NeS EeL? L? 21 17 29? 21 26 03? 21 54 25? 338 Oct. 2 NP S L? M F EP S L F 4 30 53 4 36 38 4 45 05 4 50 36 5 25 4 30 36 4 36 18 4 47 36 5 35 S-P, 5m. 45s. 3970 kms. Felt on Panama. O = 4h. 24m. 14s. 339 4 EP? S? eL? F 22 12 26 22 17 57 22 20 53 22 46 ca P and S in micros. Qr. Panama. 3725? kms. 339a 8 EeL? F? 1 50 15 1 52 09 1 55 03 34 16 340 9 EeP? 18 39 04 4-3 But Cf. Ottawa eP? S 18 48 07 9 18-41-52. 7670? kms. L 18 51 25 12 72 bulletin: museum of comparative zoology. No. Date 341 1913 Oct. 11 342 11 343 344 345 Oct. 11 12 14 346 23 Phase L F Ee S eL L F EeP S? cL F EeS eL F Ee eL F EeP? S? eL M L L F EeS eL F Time h. m. s. 18 57 16 19 13 29 2 08 13 2 13 05 2 29 56 3 30 47 3 49 27 30 28 50 39 32 45 07 12 02 10 9 33 34 10 00 02 10 48 ca 17 50 12 17 56 18 18 05 8 28 23 8 42 24 8 48 02 9 07 05 10 56 40 11 38 ca 15 13 22 15 17 10 ' 15 39 Periods 20 20 Ampli- tudes mm. 20 36 60 Remarks N. W. coast of Japan. Sinusoidala begin. E-W comp. not record- ing between Oct. lid. 13h. 15m. and 12d. 14h 26m. Vienna P 91). 22 m. 7s Sinusoidals set in. Japan. O east of 75° W. L. Vienna P 8-28-02. A4150kms? Vienna P 15-13-46. woodworth: harvard seismographic station. 73 No. Date Phase 347 348 349 350 351 1913 Oct. 26 352 27 Nov. 4 10 353 354 19 23 Ee F Ee F Ee F Ee F EeL Time F EeL M C F EeP? eS? eL h. m. s. 22 46 38 22 52 08 22 57 05 23 02 10 23 16 36 23 53 30 0 21 20 0 42 04 10 31 02 10 55 ca 22 11 32 22 14 59 22 20 52 23 03 47 44 41 00 IS 14 18 23 26 27 00 12 33 13 45 32 ca Periods 24 Ampli- tudes 24 22-24 10 20 40 30-24 17 Ee , 21 38 36 eL? 21 42 42 28-30 I 21 52 41 •2-2 02 01 31 1.5 Remarks Nos. 347-350 have short periods up to 15 sees. Stylus caught fuzz and dropped it during these records which may thus be artificial; but Cf . Cornell (Ithaca) No. 119 e23-17-41; F 23-25. Ottawa eL 23-17-12. P and S obscured by microseisms and diur- nal wave entanglement of lines. Vienna eL 10- 52. Record faint,; on un- damped pendulum only. P and S obscured by microseisms. Vienna P 21-31-53. No record E-W from Nov. 13d. 14h. 16m. until Nov. 14d. 13h. 53m. Stylus tilted over on joint in smoked paper. No record N-S from Nov. 17d. 20h. 53m. until Nov. 18d. 13h. 45m. Ottawa S? 3-54-14. e is eS? Cf. Innsbruck eL 21-57. Vienna eL 21-54. 74 bulletin: museum of comparative zoology. No. Date Phase Time Periods Ampli- tudes Remarks 1913 L F h. m. s. 22 05 56 22 10 31 22 22 07 s. 18 16 mm. On E-W comp. from 4h. 45m. Nov. 26 to end of run, stylus was held against rim of drum by- excessive diurnal and cyclonic tilt. 355 Dec. 21 Ee? 16 32 13 12 Comp. set up shortly eL F 16 35 12 16 40 18 16 44 12 17 06 58 16-34 20 20 before 16-28-40. P and S in microseisms. Cf. Vienna P 15-49-06. O east of Vienna. 356 25 ES 7 01 56 eL 7 08 56 20-16 A 5310? kms. Trieste F 7 10 26 A 4080. Vienna A 4280. O? in Atlantic off Af- rica? Number of Earthquakes recorded since Jan. 1, 1910. (G. M. T). Year Jan. Feb. 2 Mar. Apr. May 12 June 9 July 8 Aug. 4 Sept. Oct. 3 Nov. 11 Dec. 12 Sums. 1910 5 5 5 10 86 1911 8 11 3 5 6 6 3 2 8 7 8 5 72 1912 3 4 4 7 7 25 13 8 6 4 6 10 97 1913 9 2 10 5 5 9 10 8 1 12 4 2 77 Sums. 25 19 22 22 30 49 34 22 25 26 29 29 332 Aver. 6.2 4.7 5.5 5.5 7.5 12.2 8.5 5.5 6.2 6.5 7.2 7.2 83 Records Nos. 246, 269, 274, 276, 283, 287, 288, 291a, 297, 317, 330, are subject to some doubt. They have not been reported by other sta- tions in the exchanges sent to the University, and several of them are woodworth: harvard seismographic station. 75 associated with irregular periods characteristic of local disturbances probably caused by winds. Several similar records accord with reports from distant stations as that at Batavia, Java, as is indicated in the Remarks, and it is possible that more complete reports from very distant stations would show that these records represent the de- cadent maxima of long waves of distant weak earthquakes. They have been recorded because the periods of the wave motion display a seismic character. Record 299b was too much tangled by reason of the wandering of the stylus under the impulse of the diurnal wave to be read with cer- tainty on the E component. It was not recorded by the N damped component. It will be observed that for the 18 months covered by this report only three earthquakes were recorded whose origin was in the United States or immediately on its borders in Canada. No. 250 is correlated with shocks felt in Arizona but the records are un- satisfactory. No. 277a is evidently the record of a quake felt in South Carolina, but definite wave phases could not be determined. No. 301 is a satisfactory record of a local shock whose origin lay probably north of the St. Lawrence river on a straight line between Cambridge and Ottawa. For an account of the data compiled by Dr. Otto Klotz of Ottawa concerning this earthquake, see Publications of the Dominion Observatory, Ottawa, 1913, 1, no. 5, p. 131-152. Nos. 294-5 and 316 are records of the most important earthquakes of 1913, both in the Pacific island region. Lacunae in Records. The seismograph was out of commission from Sunday, 25 August about 15h. G. M. T. to Monday, 26 August, 13h. 18m. G. M. T. 1912. Reports from other stations do not indicate that any important earthquake was elsewhere recorded during this interval. New England Earthquakes. December 11, 1912, a moderate shock was felt at 5:15 a. m. from Augusta, Me. to beyond Fredericton, N. B. (Reid: in American Year-Book for 1913, p. 630). The shock of 28 April in the St. Lawrence valley south of Ottawa was also felt in neighboring portions of Vermont. November 3, 1913, a light shock was felt in southwestern Rhode Island. No trace of the disturbance was recognizable on the records at this Station. According to press despatches the time was variously given from 9: 30 a. m. to as late as 10:14 by household clocks. Most of the reports indicate a time about 9:30 a. M. Eastern S. T. In southern Rhode Island sounds were heard in the air like the booming of guns. In the town of Carolina a chair is said to have been overturned in the office of the town clerk. 76 bulletin: museum of comparative zoology. The motion was felt on the southwest as far as Watch Hill. It seems to have been felt only on the western side of Narragansett Bay and to have been most noticeable in the southern towns. The southern coast of Connecticut and Rhode Island appears to be a much dissected fault scarp, in the latter state of little elevation above the sea and much encumbered with morainal deposits. The occurrence heretofore as in 1847-8 of earthquakes along this line from eastern Rhode Island to New York City and southwestward along the "Fall Line" suggests that this earthquake had its origin in a slight slip along a fault on the northern shore of the New England Sounds. The absence of reports of a shock felt on Block Island coupled with the distance to which the shock was felt northward in western Rhode Island possibly points to a low angle of dip of this fault to the north. No faults have been detected in the rocks on the mainland in southwestern Rhode Island to which the shock may be attributed, but the region is heavily drift covered and the crystalline rocks of the western part of the state have never been delineated on a map available for study. In this connec- tion the observation of the late Prof. W. H. Niles on the meridianal compression of the gneisses in the quarry at Monson, Mass., (about sixty miles northwest of the Rhode Island shore) and the occurrence of similar phenomena in western Rhode Island, verbally described to me by the late Professor Packard of Brown University, deserve note as indicating the existence of a superficial compression of the rocks in southern New England in a direction consonant with the above sug- gestion of the attitude of the supposed fault-plane bordering the south coast. At the locality described by Professor Packard a ledge of rock was reported to throw off large spalls with a loud noise, in a manner and at times favoring the supposition that it was yielding to earth pressure like that exhibited in the Monson quarry. Condition of the Station: — From the latter part of June until about 1st December, 1913, the seismograph was greatly disturbed by the construction of the Ethnological Section of the University Museum adjoining the instrument room and also by the use of the basement of the Geological Section as a workshop. Educational Use of the Station: — ■ The seismograph has been regularly visited by the classes in elementary geology, and seismograms with a statement of the theory of seismic waves and their registration have formed a part of the instruction concerning earthquakes and the subject of faults in the courses in Dynamic and Structural Geology. As an adjunct to the Geological Laboratory the Station has proved to be an important object lesson in enforcing upon all classes of students woodworth: harvard seismographic station. 77 the discoveries of modern seismology. Classes from the public schools of Boston, and students of geology from neighboring colleges, also visit the Station. These visits are availed of by the Professor in charge to give a brief lecture on the entire working of the Station and the results obtained by the instrumental study of seismograms. The instrument room is provided with glass windows through which the instrument may be seen by students without disturbing the records. If the plant served no other purpose than this educational adjunct to the Geologi- cal Laboratory, its installation would have been worth the relatively small cost for so impressive an exhibit and convincing demonstration of some of the properties of the earth's interior. If as an enthusiastic seismologist has stated, "The seismograph is to the earth's interior what the telescope is to the space outside our earth," any depart- ment of instruction concerned with the geophysics of the globe should have a working seismograph as a part of its apparatus. StP 1915' Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vol. LV. No. 4. GEOLOGICAL SERIES. Vol. IX, No. 4. HARVARD SEISMOGRAPHIC STATION. SIXTH ANNUAL REPORT INCLUDING RECORDS, 1 JANUARY - 31 DECEMBER, 1914. By J. B. Woodworth. CAMBRIDGE, MASS., U. S. A.: PRINTED FOR THE MUSEUM. September, 1915. No. 4. — Harvard Seismographic Station. Sixth Annual Report, from 1 January to 31 December, 1914, G.M.T. By J. B. Woodworth. The records herewith presented continue the list published in Bull. M. C. Z. 55, p. 55-74. The constants of the Station are as follows: — Latitude 42° 22' 36" N. Longitude 71° 06' 59" W. Altitude 5.36 M. Subsoil: — Glacial sand over clay on tilted Carboniferous (?) shales. Time : — Mean Greenwich, midnight to midnight. Eye and ear comparison with Harvard Observatory through telephone. Instruments: — Two Bosch-Omori 100 kg. horizontal pendulums, with mechanical registration. Nomenclature: — Gottingen; also O for time at Origin. In the column of Remarks the following peculiar abbreviations are employed: Q, earthquake; Qf, felt earthquake; Ql, local shock; micros., for microseisms. Distance from Station to Epicentres is given in Kilometres read from Zoppritz and Zeissig's tables for the interval S-P; for eL-S from tables published by Goesse (St. Louis). O in this Report is calculated from tables of British Association based on work of Galitzin and Walker. Constants of the Instruments. Period : Magnification Damping N-S. E-W sees. sees. 22.5 24.8 50 80 var. 0 No. Date Phase Time Periods A Remarks 1914 h. m. s. s. Kms. *357 Jan. 8 e F 12 23 41 13 57 ? Record discounted ; prob- ably local wind effects. 358 13 0 iM F 10 21 47 10 21 47 10 21 49 0 Local frost crack. Nos. 358 to 361 occurred dur- ing nights with bare, frozen ground, and tem- peratures of -21°C. to -22°C. 82 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1914 h. m. s. s. Kms. 359 Jan. 13 O iMN F 12 14 26 12 14 26 12 14 32 0 360 14 O iMN F 0 46 02 0 46 02 0 46 04 0 \ 361 14 0 iMNE F 4 44 36 4 44 36 4 44 46 0.5 0 Stylus of E jumped 29 mm. 361a 20 0? S eLE? 12 03 36 12 21 44 12 35 30 6530? P marked by micro- seisms. PulkovoO:12h.00m. 13s. L 12 45 04 20 in

p Le 4 59 22 53.3N..X156.4E. F 5 14 30 374d 21 0 9 16 09 4050 O from S-P. eP S eL F 9 23 34 9 26 47 9 33 02 9 51 i Ottawa A 4300: Honolulu A 6225. Konigsberg eL 10-02 ; (Aca9260?). 375 27 0 eSN 0 55 46 1 16 38 9500 O by Pulkovo in

14 vard O ca. Oh. 53m. fromeL-S. F 2 09 Kamtchatka. 375a 28 0 L 10 44 31 11 38 18 (12500) ObyPulkovain^23°N. X 95° E. Upper Burma. *376 30 0 ePN i Sn Se eLN 0 40 32 0 47 41 0 47 45 0 53 18 0 53 23 0 55 16 3830 O from Sn-Pn. Shide O =0-41-11, in

8 4 20 17 Kms. 4100 O from Ottawa A 9600. But Graz P 3-55-38; eL 4-38 would make O earlier. O from Sydney record. Ottawa eL 17-16. F ? in next record. O from Ottawa A 6100. Cf. Manila eL? 19-55. O from S-P. Ottawa A 4450. Vienna A 9950; 013-29- 44. St. Louis A 3750. Qoff Acapulco. ca.^l2°N.,X104oW. O from Berkeley A 350. Qr. California. Vd. Bull. Seismog. Stations, Univ. Calif., no. 8. Dec. 1914, p. 167. St. Louis A 2500; O 8- 33-56. Graz says this is W of a Q at 0-03. Aachen eL 5-20-50. Graz eL 5-37. Vienna eL 5-40. Czernowitz eL 5-45. Cf . La Paz e 5-01-48. woodworth: harvard seismographic station. 87 No. Date Phase ' Time Periods Remarks *382 1914 May 26 383 28 384 28 385 29 386 June 18 0 Pe E N i es cLe Ln Le Ln Le Ln F 0 Pne Sn Se Le Ln Fn Fe 0 eLE Ln F 0 L F 0 Le F? h. m. s. 14 23 18 14 39 13 14 45 21 14 45 23 14 46 25 14 47 42 15 30 42 15 32 55 15 35 21 15 41 26 15 46 26 15 34 36 8 3 3 3 3 3 3 4 23 50 30 39 35 01 35 46 39 09 40 37 55 09 OS 09 17 58 09 18 17 02 18 20 04 18 36 4 47 20 5 27 13 6 56 20 + ? 21 22 48 21 27 31 21 32 43 Kms. (14,450) 2<4 8 23 26 20 16 3 7 6.5 16 15 3580 14 O from Pulkovo in

8 Kms. 8175 3000? 4 16>15 3 6 8 S 8-9 2 4 (11,350) (3650?) 7510? Remarks O from S-P, but cf. Heidelberg P 22-11-31; A 3190; O: 22-05-16. Cartuja P 22-12-40; A 2900; O 22-06-59: Cor- nell P 22-18-55; A 8520; O 22-06-46. St. Louis A 9080; O 22-07-19. Konia, Asia Minor; Is- barta and Burdur dam- aged.

7 Le 9 59 22 17 Ln 9 59 49 20 Le 10 01 26 10 04 12 10 07 46 10 16 28 14 17 18 20 F 10 35 ca 426 18 Le F 10 49 44 10 49 59 10 51 04 15 Probably part of 425. woodworth: harvard seismographic station. 97 No. Date Phase Time Periods A Remarks 1914 h. m. s. s. Kms. 427 Dec. 24 0 ePN ePE Sn Se 12 04 44 12 11 58 12 12 24 12 17 39 12 17 45 3900 From Sn-Pn. Ottawa P 12-11-37; A 4030; O 12-04-12. La Paz A 8700? Compare Honolulu A 3,200; O: SR2 12 20 48 10 11-56-32. eLx 12 21 54 10 Manila A 2880; O: 11- Mn 12 23 45 28 52-27 reports Qf in • F 14 15 Guam. A 2.2 mm. on record. 428 27 Of e Ln F 4 44 31 4 45 44 4 57 42 10 e = S? *429 Nov. 28 0? e? 10 40 =*= 11 30 10 11 39 22 24 O from Honolulu P 10- 54-24 A 10,320; O: 10- 40-52. Strassburg P 10- Ln 11 48 45 11 52 49 12 05 45 20 16 20 44-50; A 12,150. La Paz e 11-05-40. Manila cP 10-49-41; A 2210. F 12 08 ca 430 Dec. 4 0? eS? 16 58 25 17 10 37 3600? eL 17 13 23 17 14 08 17 14 22 17 19 18 17 25 46 23 16 14 10 16 Cf. La Paz P 17-40-40; F 17-50. F? 17 27 03 431 11 eN Ln to Ln to 2 27 52 2 30 48 2 36 32 2 45 06 2 46 06 12<1S e to F in microseisms. *432 20 0 ePE 14 09 22 14 27 54 4 11,100 98 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1914 Sn Se h. m. s. 14 33 45 14 34 32 14 35 54 14 37 23 s. 9 6 17 6 Kms. La Paz P 14-22-48; A 9590; O 14-09-53; Cor- E 14 43 31 15 nell e? 14-34-19 = S; N 14 43 42 13 eL 14-52-55; A = 10- eL 14 54 19 14 56 57 14 57 39 14 58 20 14 58 21 15 00 37 15 04 54 15 06 08 43 44 40 36 28 20-18 24 450; O: 14-09-22. On coast of S. Damara- land? F 15 51 433 Dec. 25 0 Pn Pe Se Sn eLE Ln F 3 42 03 3 47 14 3 47 17 3 51 17 3 51 18 3 54 45 3 56 37 4 07 2490 OfromSE-PN. Ottawa A 2800; O 3- 41-58. Cornell A 2500; O 3- 41-58. Harvard 0 5 sees, late? Georgetown eL 3-51. In or near W. India Ids. Earthquake felt on Ja- maica 10:45 p.m. Standard time (Vd. Jamaica Weather Report for Dec. 1914, No. 437, p. 4. woodworth: harvard seismographic station. 99 Number of Earthquakes recorded since Jan. 1, 1910. (G. M. T.). Year Jan. Feb. Mar. Apr. May June July Aug. Sept, Oct. Nov. Dec. Sums. 1910 5 2 5 5 12 9 8 4 10 3 11 12 86 1911 8 11 3 5 6 6 3 2 8 7 S 5 72 1912 3 4 4 7 7 25 13 8 6 4 6 10 97 1913 9 2 10 5 5 9 10 8 1 12 4 2 77 1914 2 6 11 5 5 9 8 10 2 9 5 4 76 Sums 27 25 33 27 35 58 42 32 27 35 34 33 408 Aver. 5.4 5.0 6.6 5.4 7.0 11.6 8.4 6.4 5.4 7.0 6.8 5.6 81.6 In addition to the 76 records above counted for the year 1914, the list includes seven local small shocks referred to frost. Of the 76 records, 11, regarded as probably of seismic nature, have not been confirmed by reports from other observatories, and two of these records viz. Nos. 419 and 426, are possibly reflected waves of the preceding record in each case. With the outbreak of hostilities in Europe, the monthly bulletins from stations in Germany, and of weekly bulletins from stations in Austria-Hungary, ceased to come. Later in the year reports were renewed from Heidelberg, Hamburg, and Strassbourg. In the mean- time, a request to establish an exchange of data was received from the observatory at Barcelona in Spain and later from Catania, Italy. The newly established station at La Paz, Bolivia, also entered into an exchange during the year. As will be noted in the column of Remarks in the preceding lists, data bearing on the position and time of oc- currence of many distant earthquakes has been limited to reports received from Manila, the U. S. Coast and Geodetic Stations at Hono- lulu, Sitka, Tucson, Vieques (Puerto Rico), and Cheltenham, and the observatories at Ottawa, Berkeley, Santa Clara, Ithaca, and St. Louis. As in former years by far the greater number of shocks recorded in these lists had their origin beyond the borders of North America. Data are not at hand to determine the epicentres of most of the earth- quakes registered. Notable among the earthquakes of great intensity are those of May 29 (no. 385), and June 25 (no. 392) in Sumatra, in equatorward progression. Determination of time at Origin: — An innovation has been made in 100 bulletin: museum of comparative zoology. this Report in the introduction in the tables of the calculated time at which an earthquake took place. The symbol O employed for the initial phase of seismic action at the Origin is based on the transmis- sion time of the registered phases to a given station. In previous reports where calculations for O have been given, they were based on tables by Benndorf now some years old. The more accurate curves for the known speed of propagation of the phases P, S, and L constructed by Prince Galatzin and by Walker, and published by the Seismological Committee of the British Association in the form of tables expressing distances in degrees of arc upon the earth's surface were with suitable interpolations converted into others in which the distance appears as kilometres for this report. The initial phase O standing at the head of the line of phases against the date should be common to all reports of the same earthquake where correct time and satisfactory registration have been secured. A variation of a few seconds in the deduced time at origin is probably to be expected and in the present state of seismology appears una- voidable. Any wide departure affecting the minute given points to a probable misjudgment in reading the phases' of a record. I have printed O and its time in italics to indicate that the data are deduced times and not registered or observed phenomena. In the column of remarks O will be found in several instances as deduced from the data furnished by several stations for the same earthquake. In several instances where the Harvard record began with the Long or Rayleigh waves (eL), O has been given as determined by data from other stations and the distance from Cambridge to the epicentre has been found from the interval eL-0 (read eL minus O). On the assumption that the reading of the records for eL gives the time of appearance of this phase correctly, and from the known rate of travel of L waves, 3.53 kms. per sec. or 125.42 miles a minute, it is possible, as Milne pointed out, to obtain the distance from a station where P and S are suppressed. Where P and S have been legible the distance has been read off from the tables published by Zopprits and Zeissig. In a few cases where the interval eL-S had to be used, the distance was taken from the admirable tables worked out and published by Pro- fessor J. B. Goesse of St. Louis University. But in this case as with the interval eL-O, error is apt to creep in from the uncertainty attend- ing the fixation of time at which the phase eL appears in the seismo- gram. In both cases eL is apt to be read too late, and the distance to be made too great. The record of amplitudes has been omitted except for an occasional woodworth: harvard seismographic station. 101 note under the Remarks concerning the apparent amplitude as meas- ured on the seismogram. Inasmuch as the air dampers provided for the Bosch-Omori tromometer suppress all but the heaviest distant records, it has seemed better to obtain the record of the phases P and S where possible then to seek to record the amplitude of the earth particle or technically the intensity under conditions which would prevent the registration of more than a few earthquakes. Earthquakes in trains: — Earthquakes often come in groups asso- ciated in time and place. Within these groups there is observable at times a capricious progression in direction. As an example of this action, there may be cited an instructive series of earthquakes in the Mediterranean region partly registered at this Station and partly reported by the press despatches. The group began with a destructive earthquake in the province of Konia, Asia Minor, about 22 hr. 3 mins. on October 3rd, 1914 (see record no. 417). On October 17th, a strong earthquake visited Beoetia in L. 38°.3 N., a point westward along the mountain axes. On October 26th, a shock was felt at Turin in Italy, in L. 45° N., beyond the northern turn of the Apennines. On the following day, the seismic force was manifest on the south at Florence in L. 43°.7 N. Shifting southward and equatorward along the geo- logical structure trends as if vulcanism and seismicity were in that field in causal relations, the subterranean stress found expression in the increased activity of Vesuvius on November 4th. Three days later, on the 7th, Etna yet farther south, began to rumble. On November 28th, to the east of Etna a shock was experienced in western Greece, a further step toward Etna of the Konia-Beoetia progression. A pause then ensued, long enough for one to realize that two trains of earth- quakes had approached the active focus of vulcanism and seismicity in Italy, one from the east, the other from the north. On January 13th, 1915, the disaster of Lago di Fucino took place in L. 42°? N., with the destruction of Avezzano and surrounding towns, a back-step in the path of the movement which in October and November concentrated upon the toe of the boot of Italy. Six days later, on the 19th of Janu- ary, a destructive shock occurred in Calabria again on the south near or at Cosenza. What this march towards Etna means, the future alone can tell. So far we are able to discern only a crustal adjustment beginning on the outskirts in Asia Minor on the east, and near the Alps on the north: trains of earthquakes follow along the geological structure as if set off by the shift of stress towards a centre. The equatorward shift of shocks in small groups at brief intervals is not infrequent in the northern hemisphere, but the opposite behavior 102 bulletin: museum of comparative zoology. is not wanting. A striking case of equatorward shift of seismic stress is recorded in the Report for the year 1910. On January 22nd, a sharp shock was registered which had its origin near Seydisfjord, Iceland, at 8h. 47m. 51s. G. M. T. on the Arctic Circle. At about 8h. 30m. p.m. (lh. 30m. on the 23d, G. M. T.), a slight shock was felt near Portland, Me., in L. 43° 30' N. On January 23rd, at 18h. 49m. 19s. G. M. T., an earthquake occurred off the Lesser Antilles which was felt at St. Vincent. Quiet reigned for weeks before and after over the North Atlantic border. The intervals between the first and second, and the second and third of these shocks much exceeds the limit of duration of the vibrations set up in the globe by a primal great shock. On a globe recovering the normal figure of ellipticity deformed by circumpolar ice-caps, it is to be expected that adjustment in high latitudes affecting the polar flattening would meet with a response in the equatorial region. Inas- much as the polar regions were during the glacial period the seat of the perturbation, it is natural to suppose that by reason of the disap- pearance of the ice, seismic disturbances would originate there and be propagated southward. The postglacial adjustment of the figure of the earth so far as it took place by faulting should give uplift in high latitudes, downsinking in low latitudes, and indifferent movements or lateral motion in middle latitudes. The uplift of 42 feet in Russell Inlet, Alaska, described by Tarr and Martin as taking place in 1899 in a region of retreating glaciers, the San Andreas fault earthquake of 1906 in California with a lateral motion of 16 feet, are accordant with this hypothesis. The Mino-Owari fault of central Japan in 1891 had a large lateral displacement, as well as an indifferent vertical move- ment since the motion was reversed either side of a mid-point in the length of the dislocation. But facts are wanting on which to base any conclusion as to the present tendency over the entire field of active faults. A similar equatorward progression of small shocks is apparent in the records of New England for the years 1842-1843. The most striking instances occurred in the year 1847, during which two lines of shocks beginning on the northeast in Nova Scotia on one side and in Ontario on the other seem to have concentrated on Boston and to have been followed by an earthquake on the "fall-line" as far south as Philadelphia. The coastal series comprised a shock at Yarmouth, N. S., on January 1 ; at Camden, Me., on February 2nd; at Livingston, Me., April 1; from Boston to Nantucket, on August 8 ; from Newport, R. I., to Philadelphia, Penn., on September 2nd. Prior to the Boston W00DW0RTH: HARVARD SEISMOGRAPHIC STATION. 103 shock of August 8, an interior series is recorded from north to south (-east) as follows: Grafton, Ontario, on January 8; Albany, N. Y., January 11; at Deerfield, Mass., on February 2nd; then north of Albany at Glens Falls on July 9, preceding the Boston shock of August 8. From 1848 to 1851 the seismic action played back and forth, on the whole with shocks on the south preceding occurrences on the north. The southward march along the coast from Nova Scotia was repeated in 1853. The records begin with a shock in the interior on the western slope of the Adirondacks at Lowville, on March 13. Next there was a shock at Ottawa on May 24. Ten days later, on June 3rd, at Bridgeton, Nova Scotia. 44 days later, on July 17, in southwestern Maine; after 52 days, on September 7, at New Bedford, Mass. In short, an analysis of the data from 1840 to 1870 exhibits midst a jostling interaction in various directions marked periods of steady southward progression of shocks in series. The Anglo-Saxon Chronicle mentions six earthquakes winch took place in England during the 10th and 11th centuries. The first one on the calends of May 1048 was felt at Derby, Wick, in Worcester, and elsewhere. There was a "great" earthquake in the year 1060 on the Translation of St. Martin's (Nov. 11), the place of which is not stated. Again on the eve of St. Michaelsmas (September 29) in 1119, Worcestershire and Gloucestershire were shaken. On the eighth clay before the calends of August 1122, Gloucestershire and Somersetshire were shaken. Lastly, in this group, on the night of the mass of St. Nicholas (December 6), 1129, a little before day, "there was a great earthquake," the locality of which however is not given. Now Derby, Worcester, Gloucester, and Somerset are shires succeeding each other from north to south in the order in which they were visited by earth- quakes in this mediaeval account in the years 1048, 1119, and 1122, at long and irregular intervals within the space of a man's life. I have cited this document in order to show that the phenomenon of south- ward shift of epicenters in the northern hemisphere is not peculiar to our own time or a single region. Hours at which Earthquakes have been registered at the Harvard Station. — The International Catalogue for 1907 includes a list of more than 6400 earthquakes. The Harvard records show an average of about 81 per annum, too small a proportion of the total annual registration for the world to be made the basis of other than a fewr limited problems in seismology. This lj% of the total how- ever reveals upon a statistical study certain features having a prac- 104 bulletin: museum of comparative zoology. tical utility in the conduct of the station. The following table has been drawn up showing the G. M. T. hours at which earthquakes have been registered for the years 1910-14. Hours of Earthquakes registered at Harvard. G.M.T. 0 1 2 3 4 5 6 7 8 9 10 11 Local 7 8 9 10 11 12 1 2 3 4 5 6 A.M. 1910 3 1 1 1 3 1 4 2 5 1 2 2 1911 2 2 6 1 5 4 3 1 1 1 3 3 1912 1 1 2 3 3 0 0 7 3 6 4 2 1913 4 4 2 5 3 2 1 4 6 4 5 3 1914 3 0 3 8 8 4 3 3 2 5 8 2 Sums 13 8 14 18 22 11 11 17 17 17 22 12 G.M.T. 12 13 14 15 16 17 18 19 20 21 22 23 Local 7 8 9 10 11 12 1 2 3 4 5 6 P.M. 1910 0 2 1 1 0 0 3 4 1 1 0 1 1911 2 4 3 0 3 1 7 3 2 3 3 5 1912 9 3 3 3 5 7 8 2 2 8 4 5 1913 5 3 2 4 2 8 7 2 2 4 2 4 1914 4 2 2 3 3 6 3 4 3 1 4 2 Sums 20 14 11 11 13 22 28 15 10 17 13 17 The table shows a tendency to maximum frequency at 4hr., 10hr., and 18hr. When the 6400 earthquakes of the 1907 list for the world are analyzed in the same way as to the hour of their occurrence, maxima of frequency appear at 3hr., 10hr., and 17hr. It thus comes out that the records of this Station within five years, though only about 6 per cent in number of those for the world in the year 1907, bring out a peculiarity of the horary occurrence in absolute time. Obviously it is wise to avoid disturbing or adjusting a seismograph at the hours of maximum expectancy of earthquake registration. As woodworth: harvard seismographic station. 105 the registration may take one or more hours, the hour succeeding to those named should also be set aside for that purpose. As there is a maximum registration at 18 hours G. M. T., i. e. between 1 and 2 p.m. in 75th meridian time west, in eastern North America, that hour is the best during which to observe the registration of earthquakes on seismographs with mechanical registration if it is desired to witness this sight. The observer who watches his instruments during that hour will sooner or later be rewarded by the exhibition of his seismo- graph in action. The large earthquakes originating during the 18 hr. interval G.M.T., midnight to midnight, are according to Milne's lists for 1904-1910 not less than 10 in various latitudes north and south of the equator be- tween 135° and 150° east longitude as compared with six, the highest number occurring at any other hour in the same sensitive gore of the globe. In 1910 alone five large earthquakes were traced to the same gore at the same hour of the day. The persistence of this 18 hour maximum is presumably due to an ascertainable relation between the state of the crust in the gore of maximum frequency and some regularly recurrent phenomenon, such as the passage of a change in atmospheric pressure. This hour in longitude 135 to 150 East corresponds within 40 degrees of the equator to the time of passage of the morning mini- mum of atmospheric pressure from 4 to 5 A.M. local time counted from one standard meridian to another. The chief morning minimum of pressure passes round the globe in advance of the sun traversing gore after gore at successive hours of standard time Greenwich. That this auroral epoch is characterized by frequent destructive earthquakes witness San Francisco at 5h. 13m. local time on the morning of April 18, 1906, Messina at 5h. 24m. on the morning of December 28, 1908, not to mention earthquakes unasso- ciated with the devastation of populous towns and cities. Early rising and an out door life are much to be recommended in earthquake countries ! The modern seismograph has shown that the crust of the earth is sensitive to vibrations imperceptible to human senses and the times at which earthquakes occur agree with the indications of the same delicately poised instrument in indicating that the movements of the atmosphere made manifest by the barometer are not without their effect on sensitive gores of the globe. If the time and place at which certain earthquakes occur are under atmospheric control, the future of seismology is brighter than it wrould be if the prediction of seismic disasters depended entirely upon the progress of the geologist's re- searches in the impenetrable depths of the solid globe. 106 bulletin: museum of comparative zoology. New England Earthquakes: — A brief account of North American earthquakes for the year is given by Professor Harry Fielding Ried in The American Year Book for 1914, p. 596-598. From this work it appears that a light shock was felt at St. Stephen, N. B., and Calais, Me., early on January 15th. Not recorded at this Station. Press despatches describe tremors felt at Eustis and in the neighbor- ing towns Rangely, Phillips, and Flagstaff, in southwestern Maine, on the evening of February 21, at 7: 15, 7: 20, and 7: 35, E. S. T. The second shock tumbled down a woodpile. Mr. Ralph Sawyer of White Rock, Me., states that a northeast-southwest fault traverses these towns. On February 10th (see record no. 363) a widely felt shock was registered at the Station whose origin appears to have been in northern New York somewhere between Watertown and Ogdensburg 120 kms. distant from Ottawa. The Ottawa record makes the time at origin according to existing formulae for speed transmission lh. 30m. 42.5s. p.m. The Harvard record gives the time at origin lh. 30m. 43s. when the long waves appearing at lh. 33m. 07s. are employed in the calcula- tion, but the record shows a motion at lh. 32m. 51s. wrhich has the same characters. In the first case the distance wTould be 580 kms. from Cambridge, intersecting with Ottawa's distance curve near or on the 45th parallel in Ontario about 75 miles west by south from that city. The shorter reading gives the Harvard distance 435 kms., and places the origin in northern New York, but making the time at origin lh. 31m. 02s. The Cornell (Ithaca, N. Y.) record beginning P lh. 32m. 10s. with distance 300 kms. meets the distances from Harvard and Ottawa also near the 45th parallel in Ontario, but the time at origin comes out lh. 31m. 27s., differing as much from the Harvard record as the Harvard record on one interpretation differs from that of Ottawa. Reid places the origin in northern New York. The earthquake was felt from Boston to Buffalo, and from Montreal to Philadelphia. In the Connecticut and Hudson valley towns furni- ture was said to have been moved in houses, school children were alarmed, and bric-a-brac was knocked from shelves to the floor. A man was killed in Binghampton, N. Y., according to the statement given to the press, by the fall of earth in a trench in which he was at work. Reid estimated the area shaken at 150,000 square miles. The hour, between 1 and 2 p.m. corresponds to the hour of the day at which shocks near and distant are most frequently registered at this Station. In Cambridge, Professor Faxon and Mr. Clapp of the Museum of Comparative Zoology, felt a rocking motion on the top floor of that woodworth: harvard seismographic station. 107 building at the maximum of motion. The open doors of collection cases swayed gently to and fro. In Boston a lady recognized seismic motion on the second floor of the house in which she was at the time. By most people the shock passed unobserved. The slight shock registered February 14th (see no. 366) was felt along the St. Lawrence River near Quebec. With Ottawa distance = 225 kms. and Harvard distance = 520 kins., the origin comes out on the south bank of the St. Lawrence River near Sorel. Frost Cracks: — Several frost cracks were registered during January and February, again during cold nights with nearly bare ground. On the night of January 13th when several of these disturbances were registered in Cambridge, Mr. J. H. Cowdrey of 722 Webster St., Needham, Mass., felt a shock at his home between 7 and 7: 15 p.m., another about 15 mins. later. Other similar shocks were noticed by him still later in the evening. Record no. 37 of March 1 was registered during a southeast rain storm on old snow. Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vol. LV. No. 5. GEOLOGICAL SERIES. Vol. IX, No. 5. HARVARD SEISMOGRAPHIC STATION. SEVENTH ANNUAL REPORT INCLUDING RECORDS, 1 JANUARY -31 DECEMBER, 1915. By J. B. Woodworth. With One Plate. CAMBRIDGE, MASS., U. S. A.: PRINTED FOR THE MUSEUM. November, 1917. No. 5. — Harvard Seismographic Station. Seventh Annual Report, from 1 January to 31 December, 1915, G. M. T. By J. B. Woodworth. The records herewith presented continue the list published in Bull. M. C. Z., 55, p. 78-108. The constants of the Station are: Latitude 42° 22' 36" N. Longitude 71° 06' 59" W. Altitude 5.36 M. Subsoil: — Glacial sand over clay on tilted Carboniferous (?) shales. Time : — Mean Greenwich, midnight to midnight. Eye and ear comparison with Harvard Observatory through telephone. Instruments: — Two Bosch-Omori 100 kg. horizontal pendulums, with mechanical registration on smoked paper. Nomenclature: — Gottingen: also O for time at origin. Constants of the Pendulums: N-S. E-W. Period 22 . 5 sees. 24 . 8 sees Magnification 50 80 Damping ratio 4:1 ca. 0:0 In the column of Remarks entries are confined to an explanation of the Harvard record, the source of A and O, and conditions of registra- tion throwing light on the accuracy or inaccuracy of the data. Addi- tional notes concerning the earthquakes listed in the tabulated times of phases are appended at the end of the Harvard list. The distance (A) of the epicentre from the Harvard Station, in kilometers, is given usually on the basis of the interval S-P, in accord- ance with the tables of Wiechert and Zoppritz with interpolations by Zeissig, published in 1910, and available for distances up to 13,000 kms. Where O is given with P and S present in the Harvard record, the transmission time P-0 (Ip as suggested by Dr. Otto Klotz) has been taken directly from the Hodograph der Normalen P Wellen fur eine mittlere Herdtiefe der Erdbeben elaborated by Mohorovicic of Agram. These and other tables necessary for the determination of A, O, and the epicentre (*), have been recently published by Dr. Klotz in Seismological Tables (Publications of the Dominion ob- servatory, Ottawa, 1916, 3, p. 19-61, 2 plates). In a few instances early in the year, A, and hence O, was determined from eL-S (Is of Klotz) from the admirable tables of Prof. J. B. Goesse, S. J., of the 112 bulletin: museum of comparative zoology. St. Louis observatory. An asterisk (*) prefixed to the number of a record indicates that some revision of the data issued in the monthly mimeographed bulletin of the station has been made. Such revision affects also the Harvard records published in the Monthly weather review, Washington, D. C, vol. 43, for 1915. Earthquakes registered during the year 1915. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. K ins 434 Jan. 5 0 ePN Se eL 23 37 41 23 44 56 23 50 40 23 54 01 10-15 3950 6 Me Ln F 0 18 22 0 32 36 0 56 24 20 • 435 10 eL? F 23 24 26 23 45 ca 20-15 436 13 0 ePE Se eLE L L Me F 6 52 31 7 02 45 7 04 17 7 11 01 7 19 21 7 22 24 7 26 25 7 27 48 8 05 ca 4 35 25 20 20 6750 Verazzano destroyed. 437 27 0 eN Le L L L L Ln F (1 09 48) 1 37 44 1 40 30 1 41 14 1 43 37 1 45 42 to 1 48 18 1 49 04 1 51 33 2 12 40 22 16 20 20-16 (7400) O from Shide. woodworth: harvard seismographic STATION. 113 No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. 438 Feb. 7 0 iPN iM F 5 16 SO 5 16 32 5 16 34 5 16 5 15 Local shock: Not reported by laymen. 439 16 0 iP M F 17 05 26 17 05 38 17 05 48 17 05 54 • 85 Not heard from. 440 16 0 P M F 19 24 39 19 24 53 19 25 05 19 25 18 100 ■ Not heard from. 441 19 0 P M F 22 24 58 22 25 10 22 25 20 22 26 52 90 Not heard from. 442 20 0 iP M C F 15 36 37 15 36 40 15 36 42 15 36 50 15 37 06 20 Not reported as felt. 443 20 0 iP L C F 19 54 13 19 54 18 19 54 37 19 55 02 19 55 18 95 Not heard from. 444 20 0 Pn F 23 08 38 23 09 48 ? Not heard from. Deflection N. No M. 445 21 0 iPN L M F 0 39 08 0 39 15 0 39 21 0 39 34 0 39 42 6 ? Not heard from. An = 6ju. 114 bulletin: museum of comparative zoology. No. 446 447 447a 448 449 449a 450 451 452 Date 1915 Feb. 21 21 21 21 21 21 21 Phase 23 0 P. L F 0 P L M F 0 P L F 0? P F 0 P L F 0 P L F Time h. in. s. 1 20 11 1 20 19 1 21 01 1 56 58 1 57 06 1 57 10 1 57 12 1 57 22 1 57 49 1 57 57 1 58 05 1 58 16 2 02 46 2 03 46 2 20 53 2 20 55 2 20 58 2 21 17 2 35 U 2 35 18 2 35 21 2 35 38 Pn 3 09 30 F 3 09 36 O 20 18 ca 0 23 13 05 P 23 13 25 L 23 13 42 F 23 14 10 Periods knis. 70? 40 45 20 30 145 Remarks Not heard from. Felt in Haverhill, Mass. (45kms.) at "8.55." p. m. Cf. 447. Phases indistinct. NoM. Lowell, Mass. reported shock felt at 9.05 p. m. Felt at Andover, Mass. Lowell reported shock felt at 9.30 p. m. (2.30) G.M.T. An = 5fi. Felt at An- dover, Mass. (30 kms.). Another at 9.35 p. m. of which there is a trace on records (N). Also 9.45 at Andover (trace on N). Phases indistinct. P 20-18-15; L 20-18-29; F 20-18-48. woodworth: harvard seismographic station. 115 No. Date Phase Time Periods A Remarks 1915 h. m. s. s. kins. 452a Mar. 25 Of 9 03 43.5 3440? O from S-P? Pe? 9 10 19 3 Phases masked by micro- s 9 15 32 6 seisms. Le 9 25 19 12 A 0.25 mm. on record. Ln 9 26 06 16 A 0.25 mm. on record. M 9 28 53 F 9 48 452b 25 0 P? iS eLN Ln F 20 47 19 20 59 42 21 01 34 21 10 02 21 23 36 21 24 38 21 46 07 21 48 6 13 20 20 9200 Phases masked by micro- seisms. 452c 25 0 P L F 22 14 06 22 14 48 22 15 17 22 15 49 260 Unheard from. 453 28 0 (18 59 23) (10140) O from Manila A 900. e 19 38 20 19 39 30 7 6 (A) from L-O. P and S in micros. Le 19 49 34 40 L 19 54 02 19 58 03 30 26 M 19 59 20 22 A 0.5 mm. on record. F 20 49 ca 454 5 eN Le Ln F 4 36 26 4 37 43 4 37 58 4 49 28 7 455 12 0 eN (U 48 48) 15 53 12 O based on Riverview. Masked by microseisms. Ln 15 56 35 16 01 59 18 F 16 05 116 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kins. 456 Mar. 20 e? 22 Ln 22 51 12? 18 F? lost in micros. 457 31 e Le F? 17 53 16 17 54 36 18 01 — Masked by microseisms. 458 Apr. 3 Le 21 04 46 21 07 43 18 F 21 25 ca 16-18 Masked by microseisms. 459 7 0? e? S?E eL L F (15 55 35) 16 11 57 16 13 46 16 15 17 16 15 59 16 20 44 16 37 8 13 10 16 4300? O from La Paz. Masked by microseisms. N comp. restrained by friction. 460 23 0 Pn Pe Se Sn Sri? Ln F? 15 29 10 15 37 21 15 37 23 15 43 45 15 43 46 15 46 04 15 48 42 6 6 16 4670 P and S strong; LL weak. F lost in microseisms. 461 28 eE L F 4 10 04 4 13 28 4 17 38 4 41 ca 20 20 N record faint. 462-3 4 May 1 0 ePN ePE Se Ski? Sr2 eLE 5 00 OJf. 5 12 16 5 12 21 5 22 25 5 28 14 5 28 39 5 37 29 32 8980 Mean 0:5-00-11. Kurile Islands? woodworth: harvard seismographic station. 117 No. Date Phase Time Periods A Remarks * 1915 h. m. s. s. Kins 462-3 May 1 MlN M2 Cn F? e? 5 46 15 5 50 07 5 53 41 5 57 29 8 17 9 29 17 57 mm. trace. 67 mm. trace. No trace N. Le 9 32 31 20 M2 which has travelled L 9 34 06 16 48980 kms. at 180 kms. ± L 9 36 40 15 per min. F 9 38 ca 464 May 5 Of 11 17 8730? 0?fromeL-S? Pin S? 11 39 31 8 micros. eL 11 53 50 18 Le 12 19 07 Ln 12 19 31 Le 12 20 49 12 33 31 20 20-15 - F? 12 50 465 6 0 ePE ? S eL M to F 12 08 02 12 16 26 12 19 55 12 22 58 12 33 44 12 33 59 12 35 14 13 20 6 4820 466 8 0 e to (IS 42 58) 14 44 42 15 10 var. O from Cartuja (Granada). 467 12 0 ePE eE eN eLE Le Le F? 10 29 42 10 39 29 10 42 14 10 43 02 10 55 23 10 57 04 10 59 26 11 10 17 11 30 8 24 15 6075 O from eL-P. S ill-defined. 118 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Ems. 468 May 21 Of 4 19 — O by Cartuja (Granada). 0? 4 27 46 8800? See note p. 130. eN 4 40 00 - eLE 5 04 36 S uncertain. Le 5 08 09 5 10 30 5 14 00 16 24 16 F 5 30 20 469 June 1 0 ePEN Sn Se SRiN Srie eLE Ln Le Me Ce F 14 43 50 14 52 29 14 59 13 14 59 17 15 02 37 15 02 41 15 05 06 15 07 09 15 08 47 15 12 33 15 17 03 16 15 15 15 26 5100 Sinusoidals set in. 470 6 0 eE? (19 36 25) 20 16 26 O by Riverview (Sydney). See note, p. 131. P and S in microseisms. Le 20 38 07 30-20 Sn? 20-33-54. F 20 50 ca 471 6 7 0 Pn Pe Sn Se eLE eLN? Fn? Fe 21 29 37 21 39 32 21 39 34 21 47 32 21 47 34 21 54 14 21 54 30 22 58 0 20 ca 6450 Se undamped of large amplitude. Undamped pendulum gave MM at 24-47-53; 21-49- 31; 21-50-32. No decided Mn. 472 22 0 eP Se 3 24 22 3 34 40 3 42 58 6 6790 woodworth: harvard seismographic station. 119 No. Date Phase Time Periods A Remarks 1915 h. in. s. s. Kins. 472 June 22 L F? 3 43 42 3 50 48 10 LL indistinct. 473 23 0 eP?N S eL F 4 00 21 4 06 28 4 13 45 4 17 31 4 18 08 4 54 ca 6 10 4110 O from eL-S deciphered in light of published data. 474 23 0 eS? eL Mn F 4 58 34 5 11 20 5 14 31 5 14 38 5 35 3850 E comp. gives different but more doubtful readings. Short period phases. 475 27 Of Le F (15 25 46) 15 51 16 16 22 O from Strassburg. 476 July 8 0 (22 30 48) 7700? O from Honolulu. Le 23 08 41 23 12 27 23 14 45 15 28 24 With Harvard eL? 23-08- 41, A comes out ca. 7700. North. F 23 25 56 477 22 Of ePN Sn Se eLE Ln F 4 06 08 4 16 44 4 25 20 4 25 36 4 30 02 4 32 52 4 46 00 7140 Readings doubtful. *478 25 Of 20 47 26 7400? ePR? 21 06 56 7 eP doubtful. Le 21 18 12 28 Not legible on N comp. F 21 49 00 479 29 Of 10 120 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. 479 July 29 Le F 10 55 58 10 59 46 11 04 22 20 15 480 July 31 0 Pe Pn Pre Pre Se Sn Sre eLE Ln Le Ln Fe 1 31 26 1 42 58 1 43 00 1 45 48 1 47 20 1 52 28 1 52 40 1 58 26 2 03 02 2 03 56 2 10 10 2 19 54 4 21 00 60 22 14 8200 | | 481 Aug. 3 0 Le Lri f (IS 04 27) 14 16 04 15 06 10 15 47 12 14780 O from Honolulu A8920. 482 6 0 eP? S eLN Le F (13 12 03) 13 23 25 13 35 09 13 55 18 14 00 53 14 55 20 24-22 9000 O from Sydney. eP in micros. 483 7 0 (15 04 16) O from Barcelona A1510. e L F 15 31 09 15 39 27 15 46 05 16 07 ca 20 16 - 484 18 19 0 e?E eL? L L (23 56 42) 0 21 15? 0 30 20 0 40 23 0 53 03 15 24 O from La Paz. woodworth: harvard seismographic station. 121 No. Date Phase Time Periods A Remarks 1915 h. m. s. s. l\ iii- 484 Aug. 19 L F 1 19 04 1 25 ca 16 485 Sept. 6 0 e L L F (17 20 36) 17 53 39 18 16 55 18 22 15 19 22 15 10,300? O from Riverview. 486 7 0 / 20 30 3580 N damped 4:1. E un- iPE 1 27 19 2 damped. O from S-P. N 1 27 21 2 iR 1 27 51 iR 1 27 56 iR 1 28 33 iR 1 28 40 iSN 1 32 41 iSE 1 33 54 eLE 1 34 23 26 Me 1 35 54 eL,N 1 37 01 Me 1 38 07 1 38 35 Stylus off drum. Mn 1 39 42 Stylus off drum. E 1 39 44 1 40 01 Stylus on drum again. Off drum 2d time. Mn 1 40 53 1 40 58 < On drum again. Off drum 2d time. Me 1 41 03 1 42 58 On drum again. Off drum 3d time. Mn 1 43 20 On 2d time. Me 1 44 05 1 44 21 On 3d time. Off 4th time. Cn 1 45 03 Me 1 45 22 1 46 11 1 47 14 On drum 4th time. 7thMonE. 8th M on E. Ce 1 50 02 Lrn 2 35 03 12-14 Fn 2 59 56 Damped pendulum. Fe in next. 122 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. *487 Sept. 7 0 eSN eL L F 4 28 42 4 35 31 4 40 50 4 44 25 5 05 3610 *488 7 0 e L L F (4 58 07) 5 10 30 5 15 34 5 20 19 5 37 ca 10 O by La Paz. *489 7 0 ePN Pe Sn Se 12 48 28 12 54 45 12 54 59 12 59 43 13 00 27 3220 eL to F lost in changing records. Hour in Bulletin given as 7 (local) instead of 12 G.M.T. 490 7 Of eP? S? L L L F 20 39 52 20 45 53 20 49 39 20 53 44 20 59 12 21 02 47 21 33 7 3040? Times uncertain from doubtful setting of ticker. 491 Oct. 2 0 e (23 41 — ) 23 58 12 O from Berkeley. Northern Nevada. See Se 23 59 55 6 492. 3 Le F 0 01 22 0 05 52 8, 10 N component out of com- mission. 492 3 0 e Se Le F (1 48 35) 2 03 17 2 06 35 2 08 50 2 25 22 10, 12 O from Berkeley A 340. woodworth: harvard seismographic station. 123 No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. 493 Oct. 3 0 ePE S eL Mi F 6 53 12 7 00 06 7 05 40 7 10 36 7 12 11 8 57 ca 3780 Northern Nevada. See note p. 137. 494 11 0 ePE ePE S eL,E Ln F 19 33 23 19 38 25 19 38 44 19 42 24 19 45 22 19 48 51 20 40 3 10 11, 12 2450 495 12 Of e eLE? L F 22 (circa) 22 19 38 22 22 00 22 28 10 22 43 ca 17,24 15 No trace on N. e in micros. 495 12 Of eE eL? (21 29 35) 22 19 38 22 22 00 17-24 20 O from Cartu ja (Granada) . e in microseisms. L 22 28 10 15 No trace on N, damped 4:1. F 22 43 ca 496 Nov. 1 0 eP Se Sn eLE Me LRi F 7 24 31 7 37 13 7 47 06 7 47 52 8 09 59 8 20 28 9 50 36 10 33 6 18-20 9590 From S-P. eP in micros. 496a 18 Le F? 4 55 49 4 58 49 20 497 21 0 ePE 0 13 35 0 20 46 3900 From eL-S. S-eP gives A3850; O : 0-13-39. 124 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kins. 497 Nov. 21 Sn Se eLE eLN 0 26 33 0 26 35 0 29 54 0 30 00 Mn 0 33 14 16 A trace on 'gram, 30 mm. Me 0 33 58 Stylus left drum, returning Me 0 35 57 at 1-35-34. Cn 0 36 03 Maxima of E undamped Ce 0 39 50 less than Mn damped 4/1. F 1 45 ca 498 26 0 e? (19 12 01) 19 27 34 0 from Balboa Heights, e to F masked by micro- L 19 31 46 20 seisms. L 19 36 14 to 19 39 14 16-13 498a Dec. 3 Ln L F 3 42 10 3 47 4 06 25-30 499 6 0? e? eLE L Lri F 20 26 ca. 21 30 35 21 49 15 21 50 30 to 21 52 28 22 20 00 to 22 22 22 22 59 20 12 16900? A? from Lri-L = 30.75 mins. P and S masked by micro- seisms. A decreases suddenly. 500 7 0 Pe S L F 10 38 26 10 46 20 10 52 37 10 57 08 11 28 6 4500 501 7 or iP 12 SO 25 12 35 28 2 2460 woodworth: harvard seismographic station. 125 No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. 501 Dec. 7 s? eL L F? 12 39 30 12 41 36 12 53 34 13 10 02 to 13 11 39 16 10 P? 12 41 36; another quake ? F lost in microseisms. Changed records at 13h. 35m. 30s. 501a Dec. 7 O iP Le Ln F (18 40 09) 18 43 35 18 47 50 18 48 14 18 50 ca 4 0 from St. Louis records. Reported near Cairo, 111. ' 502 8 e? IS 25 53 11 Record of doubtful charac- L 18 33 46 70 36 62 ter. Preceded and followed by similar disturbances. L 18 39 05 26 L 15 44 14 to 18 46 24 15 F indeterminate. 503 12 O Pn 21 02 01 21 09 19 3 4000 iP 21 09 35 4 iP steady-mass thrown ePE? 21 10 34 south. Sn 21 15 06 Except Pn, record much Se 21 15 23 masked by microseisms. Ln 21 18 20 Le 21 18 22 F? 21 35 30 F masked. 504 17 Le F 5 57 29 5 58 31 16 Masked by microseisms. 505 17 O? e? 7 40 21 7 54 11 4345? eS? A from L-S? Le 7 58 30 20 Not registered on N. F 8 15 12 126 bulletin: museum of comparative zoology. No. Date Phase Time Periods A Remarks 1915 h. m. s. s. Kms. *506 Dec. IS 0 e? (18 26 33) 18 48 7700? O from La Paz. Harv. A from L-O. Le 19 00 14 27 Record in tangled lines; L 19 05 13 15 deciphered on identifica- F? 19 30 ? tion of hour-line with La Paz. 507 19 Of Le? F (20 23 ca) 21 23 ca 21 44 ca O from Riverview. 508 28 0 (23 88 U) O from La Paz. 29 Le F? 0 12 34 0 17 58 e earlier? Much masked by microseisms. 509 l 31 0 eP Pri Se Sn eLN Le Me F? 12 19 23 12 27 38 12 28 57 12 33 53 12 34 00 12 40 25 12 41 13 12 45 03 13 42 10-12 16-14 4810 509a 31 Of 23 07 04 3300? Minute ticks failed; time ePE? 23 18 56? 2 interpolated. Not regis- S 23 18 4 6 tered N-S. Sri 23 20 10 8 eLE 23 32 50 8 woodworth: harvard . seismographic station. 127 Notes on Earthquakes, with abstracts from data received from other observatories. 434. Jan. 5.— 0 : 23-37-41. Cf. Heidelberg A2920? 0 : 23-33-13. Athens P 23-38-30; A8850; O: 23-26-25; "Epicentre en Virmanie." Ottawa A4220 ; 0 : 23-37-33. La Paz A10, 040 ; 0 : 23-32-26. Bata- via A2780; 0:23-27-44. Shide reports 0:23-26-28; and epicentre \119°30' E., 5° S. Strassburg eP? 18-36-11. 507. Dec. 19. O? 20h. 23m. ca. by Riverview (Sydney) A5320? Cf. La Paz iP 20-34-00: eL21-30. Honolulu e2 1-07-00; M2 1-14-00. Manila eP 20-19-10; A2000; O: 20-14-57.6. Epicentre Betuan, N. Mindanao. 508. Dec. 28. O? 23-40^8 from Balboa Heights P 23-44-21; A 2000. Cf. Ottawa A3800?; 0:23^5-58? Washington 29d. L?0- 03-05. Honolulu 29d. eO-08-24; M 0-25-12. Cartuja (Granada) 29d. iS 0-01-30; A9515?; 0:28d. 23-38-16? Barcelona 29d. eL 0-33-04. Riverview (Sydney) 28d. e23-58; 1; eL 29d. 0-31.9. Cf. La Paz 28d. iP 23-40-08; A620, from L-P; O: 23-38-44. Manila e23-59; F 0-40 (29d). 509. Dec. 31. O: 12-19-23. La Paz A8630? O? 12-19-16. Tucson P12-23-36; A4225?- Washington P 12-27-09; A3055; O: 12-21-08. Honolulu P 12-27-54; 1680; O: 12-24-19. Lawrence, Kans. A2750; O: 12-19-36. Cheltenham L 12-41. St. Louis A2850; O: 12-24^8. Northfield L 12-39^7. Ottawa A3200; O: 12-19-45. Vd. Toronto, Victoria. Barcelona eL 13-02-38. River- view (Sydney) e 12-48.8; eL 13-05. Mean O of stations giving 19m. is 12h. 19m. 30s. Strassburg eL? 13-02. Heidelberg eL 12-55. Manila eP 13-13-22; F 13-16. 509.a. (Dec. 31.) Two earthquakes: 0:22-25-17; A2820; and 0:23-00-36; A2720; according to Riverview (Sydney). Honolulu A1180; 0:23-00-08. But American and Canadian records point to allotrocentric disturbance; though it is possible the readings are due to the microseismic character of the preliminary tremors from the earthquakes reported by Riverview. The Harvard record displays 142 bulletin: museum of compakative zoology. short period L waves characteristic of a weak not distant earthquake. Ottawa A3200; 0:22-. Cartuja (Granada) A4700; O?23-06-08. Manila eP 22-54-22; F 57m. Then e 23-05-17; S 23-09-23; A?2510; O: 23-00-08. Cf. Athens P 23-14-05; A2320; O: 23-09-17. An examination of the abstract of the records above given brings out the character of seismological registration at the present time in the United States. It is to be expected that very distant weak earth- quakes should not be fully recorded on seismographs in this country; but it is otherwise with shocks strong enough to be made the basis of scientific investigation, when these have their origin within the con- tiguous territory of the United States. The fact that destructive shocks in southern California during the year were not registered satisfactorily at any considerable distance, implies that our seismo- graphs are not sufficiently sensitive ; in particular the seismographs on the Atlantic border show satisfactorily only the exceptionally strong earthquakes on the Pacific coast, and they fail to do much more than that for the weak earthquakes in the Appalachian belt; while slight shocks a few miles from seismographs are not registered at all. On the other hand earthquakes like that of July 31, 1915, O: 1-31-25 and October 3, 1915, O: 6-53-14, were widely registered over the United States in a manner to show that, with few exceptions, a fair degree of accuracy is maintained at most stations as regards standard time, and the interpretation of seism ograms. Number of Earthquakes recorded since Jan. 1, 1910 (G. M. T.) Year Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Sums 1910 5 2 5 5 12 9 8 4 10 3 11 12 86 1911 8 11 3 5 6 6 3 2 8 7 8 5 72 1912 3 4 4 7 7 25 13 8 6 4 6 10 97 1913 9 2 10 5 5 9 10 8 1 12 4 2 77 1914 2 6 11 5 5 9 8 10 2 9 5 4 76 1915 4 7 4 4 5 7 5 4 6 5 4 14 69 Sums 31 32 37 31 40 65 47 36 33 40 38 47 477 Aver. 5.1 5.3 6.1 5.1 6.6 10.8 7.8 6.0 5 . 5 6.6 6.3 7.8 79.5 The earthquakes counted in this year's enumeration include four local shocks, which were reported as felt. Other shocks listed in the preceding catalogue, but not heard from, have been intentionally omitted as requiring perhaps some confirmation. With a mean woodworth: harvard seismographic station. 143 annual registration of 79.5, the monthly average would be 6.6. For the first time, the data thus set forth show a tendency to develop semiannual maxima in June and December, but the capricious range of the figures indicates that this enumeration may be temporary and delusive. The middle columns of the tabulations exhibit a tendency of high monthly frequency of earthquakes to shift to later months from May, 1910 to August, 1914; but the most that can be said of the matter at present is that the amount of time required month by month to work out the seismograms at this Station varies widely within certain limits. It is to be presumed that the tabulation shows, within the range of the seismograph employed, the ordinary run of registrations during a period of least seismic action in New England. A single great nearby earthquake such as that of Plymouth in 1638, or Boston in 1755, with its train of aftershocks, would entirely alter the aspect of these statistics. Condition of the Station. The seismograph was in continuous service throughout the year, though at times one component or the other was for short intervals out of commission. On September 13 the spring driving the registering drum on the east-west component cracked and on September 15 broke down completely. For this cause the E component was out of commission during 15-19 Sep- tember. On September 29 the clock-work of the N component stopped and this component was out of commission until October 4. The E component was again out of service November 27-28, by reason of a nut working loose in the governor of the clock-work. On December 5, a change was made in the counterpoising of the stylus furnished by the manufacturers of the Bosch-Omori instrument. With the view of reducing the friction at the contact with the smoked paper, the free end of the lever-formed stylus was weighted with a small piece of beeswax, with the result that both components thus treated displayed a higher degree of sensitiveness. The results are perhaps best brought out by comparing the number of records re- ported at Harvard and Ottawa for the three months before and after the change in the instruments. 1915 1916 Sept. Oct. Nov. Dec. Jan. Feb. Ottawa, photographic Harvard, mechanical 8 6 5 5 5 4 8 14 5 11 9 10 144 bulletin: museum of comparative zoology. Previous to this reduction of friction in the stylus contact with the smoked paper on December 5, the instruments for the three months September, October, November, fell behind the instruments at Ottawa in registering some part or all of a seismogram in the ratio 18/15, i. e. Ottawa registered more shocks; for the months Decem- ber, 1915, and January, February, 1916, the ratio Ottawa/Harvard stood 22/35, that is, the Harvard instrument recorded a greater num- ber of shocks. But this increased registration at Harvard was made by the undamped component for which the friction of the stylus working in the smoked paper previously had a greater damping effect. At Ottawa both components are damped. The consequence of the removal of this slight amount of damping has been to increase resonance in the pendulum and thus to obscure somewhat the earlier phases. It has come about therefore that while a greater number of earthquakes are recorded than heretofore, more difficulty is found in reading the preliminary phases in the undamped records. Local action of distant earthquakes at the Station. In the Report for 1910-11, p. 19, an estimate was given of the time during which the ground at Cambridge was agitated during a year by the vibrations of distant earthquakes. Such an estimate naturally must vary with the sensitiveness of the seismograph depended upon for a registration of the motion. An analysis of the records of 76 distant quakes regis- tered in Cambridge during the year 1914, yields the following figures. No. of Month Quakes Duration Average Maximum Minimum mins. mins. mins. mins. Jan. 2 153.26 76.6 116.0 37.26 Feb. 6 151. 25.1 72.0 8.00 March 11 354.63 32.2 122.3 6.2 April 5 274.00 54.8 112.0 21.0 May 5 297.54 59.5 115.2 19.0 June 9 596.00 66.2 163.25 8.75 July 8 443.3 55.4 88.5 7.5 Aug. 10 477.3 47.7 103.6 1.5 Sept. Oct. 2 240.0? 408.7 120.? 46.4 9 122.0 0.5 Nov. 5 208.3 41.6 113.0 1.0 Dec. 4 137.5 36.3 83.0 16.5 The total duration of registered vibrations for the year 1914, amounts to about 60 hrs. It will be observed that at this Station certain important earthquakes have a duration varying between 112 woodworth: harvard seismographic station. 145 and 116 minutes; there is a second group lasting 122 minutes. Above and below these groups others may exist but the times range widely. Hours at ivhich earthquakes are registered. The hours at which earthquakes begin to be registered at the Station were tabulated in last year's report, with the result that maxima for all earthquakes near and distant came out as follows : — Local hours. G. M. T. Civil. 1st Maxima 1 to 2 p.m. 18 to 19. 2nd 11 to 12 p.m. 4 to 5. 3rd 5 to 6 a.m. 10 to 11. The registration hours for 1915 give a maximum of 9 records from 4 to 5 hrs. G. M. T. At no other hour did the registration rise above 5 cases. When allowance is made for the time at origin of distant shocks, it is readily understood that one or all of the hours above given would come one hour earlier in terms of the hour at which earth- quakes occur. The analysis of 638 chief earthquakes listed by the late John Milne in the Reports of the British association for the years 1904-1910, shows, upon reducing the time of occurrence to local hours at the respective epicentres, three well-marked maxima of frequency at the following hours in local time : 1st maximum 4 to 5 a.m. 2nd " 12 to 1 p.m. 3rd " 10 to 11 p.m. Minor peaks between the hollows of the tabulation come at the following hours of minor maxima : 1st minor maximum 1 to 2 a.m. 2nd " " 8 to 9 a.m. 3rd " " 4 to 5 p.m. The chief mimima fall between 5 and 6 p.m. and between 12 and 1 a.m. The concordance of the maxima of frequency in this list with the hours of passage of the morning minimum of atmospheric pressure, the morning maximum before noon (there is a lag of about one hour in this case), and the afternoon maximum of pressure before midnight, is too close to justify further delay in recognizing the trigger-effect of changes of atmospheric pressure sweeping round the globe before and behind the sun in setting off earthquakes, whatever the mechan- ism of the process may be. It will be observed that Harvard hours 146 bulletin: museum of comparative zoology. of maximum registration come in each case at the hour following the maxima shown in Milne's list. This is probably because most earth- quakes registered at the Station originate in the hour preceding that in which they are registered. Now if we take the 6,604 earthquakes distinctly recorded for time and place in the Catalogue of the International commission for the year 1907, we find a chief maximum from 3 to 4 hrs. G. M. T., a second high maximum between 10 and 11 hrs., and a third maximum at 17 to 18 hrs. The Harvard maxima in G. M. T. coming at 4 to 5 hrs., 10 to 11 hrs., and 18 to 19 hrs., show precisely the same belatement at 4 to 5 hrs., and 18 to 19 hrs. in regard to this table that they do to the 638 earthquakes in Milne's list, hence it is to be inferred that the 6,404 cases in the 1907 Catalogue converted to local time of the respective epicentres will reveal the same waxing and waning at critical hours of change of barometric pressure. At the chief maximum between 3 and 4 hrs. G. M. T., the sun is passing from noon in X135° to noon in X125° E., over the Philippines and other islands in the most sensitive seismic gore of the globe. The morning maximum of atmospheric pressure is passing or has passed westward of the advancing sun. At the same hour in absolute time the afternoon maximum of pressure is advancing from X75° W. to X90° W., between 10 and 11 hrs. p. m. in local time, and the morning minimum of atmospheric pressure, broadly from 4 to 6 hrs. a. m. in local time, is sweeping the gore between X30° E. and the meridian of Greenwich. Hence it is that the maximum frequency of earth- quakes in eastern Asia, in eastern North America and western South America, and Europe-Africa, when taken together, fall between 3 and 4 hrs. in G. M. T., or broadly as a two-hour maximum between 2 and 4 hrs. G. M. T. At this hour three of the most extended meridional sensitive gores of the globe are swept over by the tropical phases of diurnal changes of atmospheric pressure. New England Earthquakes. Several slight shocks were felt in the Merrimac Valley in Massachusetts on the night of February 21, 1915. According to press despatches shocks were felt in Andover, but more strongly southeastward towards North Reading, at 9 : 20, 9 : 30, 9 : 35, and 9 : 45 p.m. Many persons ran out of their houses. Two shocks were felt in Lowell and nearby towns, at 9 : 05 and 9 : 30, according to the same reports. The first shock was felt in Billerica Centre, and the second at Cole's Crossing in Billerica. In Haverhill a shock was felt, according to one account, at 8:55 p.m., according to another report at 8: 59. One report gives a second shock at 9: 51 p. m., and woodworth: harvard seismographic station. 147 the other 20 minutes later than 8:55. The second shock rocked houses. Windows were reported to have been broken in the Farnham district of North Andover; and dishes and books were shaken off the shelves in Andover. Dishes were broken so it is stated in several houses in the Bradford and upper Main street district of Haverhill. Mr. Preston R. Wentworth (Harvard '15) visited the district at my request and was able to verify some of the statements, but not all of them. From his investigations the intensity of the shocks appears to have risen to between IV and V in the Rossi-Forel scale, so far as can be judged by the character of the houses and objects disturbed at the time of maximum motion. The geology of this part of the state has not yet been published in sufficient detail to throw any light on the origin of these shocks. It is evident, however, that the shocks of this year were distributed along the trend of the geological formations^ from northeast to southwest. Local unreported shocks. It will be observed that a number of small unreported shocks are given in the lists for the month of Febru- ary, 1915. These are based on seismographic records identical in character with those identified with the shocks felt February 21 at Andover, and other nearby towns in the Merrimac Valley. They should be understood as " instrunientally recorded" shocks until confirmed by independent evidence. It is possible that these records arise from small earthquakes having their origin on the sea-floor off the coast of New England if, indeed, they are truly seismic records. Such records are not infrequent at this Station during the winter months. The motion of the instruments is quite distinct from that set up by frost cracks at the Station, and from that produced by local jars caused by vehicular traffic, or the running of machinery in the basement of the Mineralogical Museum adjoining the Station. While they have been listed, I have not counted the unconfirmed records among the earthquakes recorded for the year, and should advise that they be regarded in the enumeration of local earthquakes as negligible quantities. It will be noted that, while a number of supposed unfelt shocks at the distance of some tens of kilometers from the Station have been recorded during the winter months, the report contains no evidence of frost cracks at the Station. According to Prof. H. F. Reid (American year book for 1915, New York, 1916, p. 596, and personal information) the British ship "Aleppo" encountered a heavy shock at sea 300 miles southeast (not 148 bulletin: museum of comparative zoology. southwest) from Halifax on January 22, 1915. On that day and for several days prior thereto the instruments at the Harvard Station recorded violent jars which were not considered at the time to be of seismic origin. The vibrations were registered most clearly on the north-south component. Shocks of the same character were usually recorded, at various intervals between 8 a. m. and 4 p. m., from Janu- ary on Sundays when the street traffic and movements about the building were at a minimum, as well as on week-days. None of the registered shocks were reported as felt by individuals. The earthquake of February 14, 1914, referred to in last year's report has been fully described in a report by Dr. Klotz l as having its origin in 46° 15' N. and 74° 46' W., at a depth of 85 km. near the small hamlets of Labelle and Nominingue, Quebec, far below the known geological structure of the Laurentian rocks of that region, and "at two thirds or more of the theoretical depth of isostatic compensation" (Klotz). Hours at which Neiv England earthquakes occurred between 1638 and 1800. For the purpose of comparing the earthquakes of New England including the period of maximum frequency and intensity of the shocks the following table was compiled from the lists of Brigham and Lancaster. As in the previous tables 10 hrs. for instance, means at any time between 10 and 11 hrs. 0123456789 10 11 G.M.T. 7 8 9 10 11 12? 1 2 3 4 5 6 p.m. 3 7 12 15 4' 4 5 6 5 6 4 9 Shoe 12 13 14 15 16 17 18 19 20 21 22 23 G.M.T 7 8 9 10 11 12* 1 2 3 4 5 6 p. m. 375S22374342 Shocks ? Midnight. *Noon. Imperfect as are the data for such a table, the maximum cases 12 and 15 at the local hours from 9 to 11 p. m. correspond with the world maximum of frequency for earthquakes in the year 1907, and locally with the presumed mean hours of local passage of the afternoon 1 Earthquake of February 10, 1914. Publications of the Dominion observatory, Ottawa, 1915, 8, no. 1, p. 3-14, with plate and map. woodworth: harvard seismographic station. 149 maximum of atmospheric pressure. The maximum of nine cases between 6 and 7 hrs. a. m., corresponding to 11th hr. G. M. T., is also accordant with the data of 1907. The nine cases between 4 and 5 p. m. coincide with the passage of the afternoon minimum of pressure; but the data other than for the evening maximum 9 to 11 hrs. are insufficient to warrant more than the continuation of such an investigation. — I The belief is quite general about Boston that this region is now practically exempt from severe earthquakes, and that the occurrences of the 17th and 18th centuries at Plymouth, Newbury, and Boston pertain to an exhausted regime in the earth's conduct. It is well to remember, however, that from the great earthquake of 1638, felt at Plymouth, to the shocks at Newbury in 1727 is an interval of 89 years; and that the interval between the earthquake of 1638 at Plymouth and that of 1755 at Boston is 117 years. The interval between the earthquake of 1755 at Boston and the Charleston earthquake of 1886 is 131 years. These long intervals of repose and minimum seismic action lull suspicions and cause the multitude to regard what has not occurred in their father's and grandfather's days as a possibility too remote to enter into their own lives. Nevertheless it behooves us to remember that the earthquake at Plymouth, Mass. in 1638, at New- bury, Mass. in 1727, at Boston in 1744 and more strikingly in 1755, and yet more impressively at Charleston, South Carolina, in 1886, and at San Francisco in 1906, offer phenomena during more than three centuries, the time of occupation of the middle latitudes of the North American continent by European peoples, of the magnitude of the local play of the seismic force. It is evident that the intervals between epochs of great destructive force in the same locality are to be meas- ured in centuries and fractions of a century. Until science shall have discovered the signs of the return of these alarming and often diastrous earthquakes, we can only bear in mind that as we recede in the steady march of time from the epoch of one of these events we draw nearer, step by step, to the next one in the series. In an article entitled " An earthquake in New England during the Colonial Period (1755)," Mr. Frederich Brasch (Bulletin of the Seismo- logical society, 1916, 6, p. 26^2) has reprinted Professor John Win- throp's lecture on Earthquakes, read in the Chapel at Harvard College on the occasion of the "great earthquake" of November 26, 1755. As a reminder of the profound impression which that earthquake made upon the inhabitants of the metropolitan district of Boston, as the region is now frequently called, the facsimile (Plate) of the 150 bulletin: museum of comparative zoology. title page 1 of a sermon read at the time in the South Church in Boston may not be amiss among references to the literature of the earth- quakes of New England. The dates November 18th and 26th refer to the same day in old and new style, a source of much confusion in the references to earthquakes of the colonial period. World map based on Lambert's projection. In the 3rd Annual Report of the Station, I described a mercator map of the globe on which were drawn curves of equal distance from Cambridge and great circles passing through the Station and its antipodes in accordance with Lambert's projection. I have since learned that such a map was drawn in 1907 for the Station at Hamburg 2 and earlier in unpublished form for Ischia and Rome by Dr. G. Grablowitz, Director of the Central Earthquake Station in Ischia. The same type of map was drawn up for Tokyo, Japan and published in the Journal of geography (Tokyo), 1911, 23, plate 15. It is repro- duced by W. L. G. Joerg3 fig. 1, p. 51, together with a proposed map of the world on the stereographic projection, drawn in the example for Apia, Samoa (Plate 17). It must be stated that while the stereo- graphic projection is best adapted to the location of epicentres with reference to a certain station, the Lambert's projection superposed on a mercator chart of the globe is of greater use to the seismologist in determining the position of epicentres from the intersection of dis- tance curves from three or more stations. At best, the method of direct plotting on small scale maps is but approximate, and seismolo- gists have instinctively chosen the Lambert projection because it .best suits their needs of a facile means of quickly adjusting the data concerning a distant earthquake as a preliminary to more exact calculations for the determination of the epicentre. 1 Thomas Prince, A. M. Earthquakes the work of God. . . .being a discourse on that sub- ject, made public at this time on the occasion of the last dreadful earthquake which happened on the 18th of Nov., 1755. Boston, 1755, 19 pp. Appendix p. 20-23. Concerning the opera- tion of God in earthquakes by means of the electrical substance. Those interested in earthquakes of the Colonial Period should also consult the following: John Cotton. A holy fear of God and his judgements exhorted to: in a sermon preached at Newton, November 3, 1727. On a day of fasting and prayer, occasion'd by the terrible earth- quake that shook New-England, on the Lord's day night before. With an Appendix containing a remarkable account of the extraordinary impression made on the inhabitants of Haverhill, &c. Boston, 1727. 12 mo. 24 pp. Appendix 7 pp. giving The letter of John Brown. 2 G. Grablowitz. Weltkarte der azimute und der entfernungen fur Hamburg. Die erdbe- benwarte, 1907, 7, 4 pp. 8 Wolfgang L. G. Joerg. On the proper map for determining the location of earthquakes. Ann. Assoc. Amer., geog. 1912, 2, p. 49-54; with useful references to the literature of seismologic maps. woodworth: harvard seismographic station. 151 Publications. The mimeographed monthly bulletins of the Station have been published in the U. S. monthly weather review, January-December, 1915, 43, p. 41, 80, 142, 192, 244-5, 292, 528, 528, 528, 528, 525, 571, 620. On O as a symbol for time at origin. Bull. Seismological society America, 1915, 5, p. 105-106. Seismographic Stations. The data from other stations cited in this Report are compiled from various documents received at the Station in exchange. Several stations in the United States (Denver, Fordham, Honolulu, Lawrence, Northfield, Sitka, Tucson, Vieques), and in Canada (Toronto, Vic- toria), since January 1, 1915, publish their records in the Monthly weather review, Washington, D. C, but issue no bulletin to this station. Records of the U. S. coast and geodetic survey stations, also published in the Monthly weather review, since January 1, 1915, may be found for earlier years in the "Results of observations" at the several magnetic observatories. Certain necessary data con- cerning foreign stations will be found in the list entitled " Coordonnees des stations sismiques du globe et tableaux auxiliaires pour les calculs sismiques," by Dr. Sigismond Szirtes, Publications de Bureau central de l'Association internationale de sismologie, "Series A. Memoires. Strassbourg, 1908, pp. 23. Data concerning the French seismological sendee are taken from Bulletin sismologique. Bureau Central meteorologique de France, Paris. Fevrier, 1911, p. 2. Occa- sional records from foreign stations have been taken from the Monthly bulletin of the seismological committee of the British association for the advancement of science, beginning with January, 1913, including the records of important earthquakes registered at the Shide Observ- atory. A number of stations are included in the list of which only the latitude and longitude are known, for the sake of their use in de- termining epicentres. For the first publication of records of seismo- graphs in North America and the Hawaiian Islands, see papers by this title by Prof. Harry Fielding Reid in Terrestrial magnetism and atmospheric electricity, June, December, 1905, for the year 1904; including records from Baltimore, Cheltenham, Honolulu, Mt. 152 bulletin: museum of comparative zoology. Hamilton, Puerto Rico, Sitka, St. Louis, Toronto, Victoria, Washing- ton. In the following list where two observatories are located in the same city, the rule has been followed where one of them is a government institution of retaining the name of the place for the public station, and of using the name of the institution for the private observatory. Several stations in Szirtes's list have been omitted for lack of records. The stations of the British association have been included because of the records published in the Shide Bulletins since the beginning of 1913. The station included in Klotz's Seismological tables for which the epicentral constants are worked out in accordance with his method are marked by an asterisk (*). *Aachen (Aix-le-Chapelle) , Germany. Haupstation fur Erdbebenforschung der Konigl. Technischen Hochschule. Station A: Wiechert photographic horizontal and vertical 80 kg. 31° 42' N. X135° 31' E. Vd. Shide Records. *Ottawa, Canada. Dominion astronomical observatory. 45° 11' 06" N. X9° 09' 13" E. E. Oddone. Perth. *>31° 57' S. X115° 50' E. Vd. Shide Records. Pilar. *>31° 40' S. X63° 51' W. Vd. Shide Records. Pola, Austria. K. u. k. hydrographisches amt. (Abteilung geophysik). 37° 46' N. X6° 38' W. Vd. Shide Records. Rivervieiv, Sydney, N. S. W. Riverview college observatory. 490 54' N. X97° 07' W. St. Helena. 38° 38' 17" N. X90° 58.5' W. Alt. 160.5m. Foun- dation: 12 feet of clay over 300 ft. of Mississippi limestone. Wiechert hori- zontal, 80kg. Bulletin from December 1, 1910. Annual reports in Bulletin of St. Louis university (Tables and coordinates^ for St. Louis, vd. vol. 7, no. 5, December, 1911.) John B. Goesse, George E. Rueppel. *Samoa. Vd. Apia. San Fernando, Spain. Inst, y obs. de Marina. «p36°27'N. X6°12'19"W. Gen. D. T. de Ascarate. Vd. Shide records. San Salvador, San Salvador. Seismological bureau of the Republic of San Salvador. 53° 50' N. X2° 28' W. P. W. Sidgreaves, S. J. Issues earthquake records. Vd. Shide Records. *Strassburg, Germany. Kaiserliche Hauptstation fur erdbebenforschung. *48° 35.5' N. X7° 45' 57" E. Alt. 135m. Foundation; gravel. Wiechert astatic horizontal, 1000kg.; vertical 1200kg. Mimeographed records (rec'd) from October 6, 1910. Galitizin aperiodic, with gal vanometric registration; records from February 1, 1914. Records of microseisms compared with 160 bulletin: museum of comparative zoology. "Seegang" at Gris Nez, He d'Aix, Skudenes, Helgoland, and Borkum, from January, 1913. Mainka. *Sydney, N. S. W. ^33° 52' S. X151° 12' E. Vd. Shide Records. Sydney, Jes. Seism. Service. Vd. Riverview. *Tacabayu, Mexico. Comision geologico de Mexico. 48° 14.9' N. X16° 21.7' E. Alt. 198m. Foundation: loess overlying clay. Wiechert seismograph. Mimeographed records from April 28, 1913 (rec'd). Mitteilungen der Erdbeben-kommission der Kaiserlichen akademie der wissen. i. Wien. Rudopf Schneider. woodworth: harvard seismographic station. 161 *Vieques, Puerto Rico. U. S. coast and geodetic survey. Magnetic obser- vatory.