486 MONTHLY WEATHER REVIEW. NOVEMBER, 1906
H[ann], J[ulius]. Eredia iiber die Temperatur-Differenz zwischen
H[ann], J[ulius]. Mittelzeiten fur die Vegetation und die Lancl-
Hlann], J[uliuq]. Repenfall in der Stadt Oasaca. Pp. 477-478.
Hann, J[ulius]. Resultate der meteoroloyiwhen BeoLac.litungeu auf dern KodaikBnal-Observatorium in Siidindieu iin Jahre 1904.
Pp. 468-169.
McDowall, Alex. B. Sonnenflecken, LuftdruckalJweictlilligPn zii
Stykkisholin und Frosttage zu Greenwich.
-Meteorologische Beobachtungen in Arequip (Peru) 1902 und 1903. Pp. 471-462.
-Ein meteoro~ogisches Amt fiir das britibche Beich. Pp. 467-468.
Osthoff, H. Formeu der Cirrn9wolken. (Schlitss. ) Pp. 439-455.
-Prohasktr uber Blitzsi*hAden und bemerkeuswerte Blitzfornien in Steiermark iiud KRmtrn in den acihreu 19132 und lW)3. Pp. 464-
467.
-Resultate der nieteorologiqchen Beobachtungen ani Olisermto-
riuin in Quito in den .Jahreu 1901-1904.
Taudin-Chabot. J. J. Geonietrisches Zuni wgenannten Sonnt3u-
untergang; die 5 merkwiirdigen Stellungen.
Topolansky. Dauer der Blitze. P. 468.
Topolansky. A. J. Monnc! ilber r1i.n Niederschlag im Ra'bnigreich
Vageler, P. Beobachtungen wdhrencl der Sonnenfinsternis ani 30.
- Wassermangel in Nclrwegen ini .Talire 1904.
- Zur Ozonbildung in der Atmosphiire.
Defant. Berichte a u s den naturwissenschaftlichen Abteilnngen der 77. Versa~nmliiug deutscher Natni forscher und hrtze in
Meran 1905. Ahleilung 6 : Gsophysik, einschliesslich Meteorologic
und Erdruagnetismu5. P . 606.
Gerdien, H. Demonstration eines Apparates zur absoluten Mrb-
sung der elektrischen fahigkeit der Liift. Pp Son-801.
Saussure, Rene de. chlag zii eineni europtiischen iuetroro- logischen Zentralbureau. (Bericht an der lio~igress iler Sichwei-
zerischen Natnrforschenclen Gesellschaft, Luzorn, den 13 Selit.,
1905.) Pp. 852-855.
Rocca di Papa uud Monte Cavo. P. 470.
wirtschaft in Schweden 1873-1900. P. 456.
Pp. 162-463.
Pp. 475 476.
Pp. 463-464.
der Niederlanden. Pp. 47Ck471.
August 1905. Pp. 473-474.
P. 475.
P. 468.
Natumieaemchuftliche Rmdachau. Berlin. 3) Jahrgung. Nov. 3, 1905.
Physikalieche Zeilschrzft. Lcipzig. 6 Juhrg., Nov. 3, 19tIi.
Physikn2isehe Zeitwhrt'ft. Le 6 Jizkry. Der. 1, 1 1 l i .
Das Wetter. Berlin. 2.2 Jrrhrgung. Noli., 190 7.
Sieberg, August. Einiges iiber den Schnre. Pp. 241-249.
Journal of the Meteorological Society of Jnpnn. Tokyo. 24th year. Ocl.,
Wada, Y. Regime des pluies a u s environs de Tcheniulpo. Pp.
190.5.
1-7.
RECENT ADDITIONS TO THE WEATHER BUREAU LIBRARY.
H. H. KIMEAT L. Librariau.
The following titles have been selected from among the books
recently received, as representing those most likely to be useful
to Weather Bureau officials in their meteorological work ani1
studies. Most of them can be loaned for a limited time to
officials and employees who make application for them.
American Catalog, 1900-05. Containing a record under author, title, subject and series of the
books published in the United States together with a directory o f
publishers. Isii, 1333 pp. 4O. New Tork, 1905.
Britton, Nathaniel Lord, and Brown, Addison. Illustrated flora of t h e northern United States, Canada and the
British P1)ssessious from Newfoulidland to the parallel of the
southern boundary of Virginia and from the Atlantic Ocean west- ward to tlie 102d meridian. 3 v. 4O. New Pork, 1905.
Davison, Charles. Study of recent earthquakes. sii, 255 pp. No. London, 1905.
NOTES AND
A GUIDE TO THE OBSERVATION OF EARTHQUAKES.
The Strnssburg Seismologicd Stntion has tlistrilmted n
circular * throughout tlie \wrlcl to :all Gernixn consul^; tlint will,
i t is hoped, concentrate our efforts to record ani1 collect rarth-
quake data. As we nom reprint this circular we will rqiiest
all to send their oherrations to the nearest consulate o f the
Gernian Empire, or to the Geriiim C'onsul-General in Nen
York, or direct to Prof. H. F. Reid, Johns Hopkin5 Unirersity.
Baltimore, Mcl., or to the Etlitor, who will forward thein prc11)-
Reprinted from Beitrage zur Geophysik, 1905. VI1 Bd. 1 heft.
Ebert, HCermann].
Geographisches Jahrbuch. v. 27, 1904.
Gray, Asa.
Anleitung zum glasblasen. Ed. 3, enl. sii, 1'20 pp. 8O. Leipzig,
1904.
Hrsg. von Hermann Wagner. 2 pts. in 1 v. 80. Gotha, 1905.
Fieltl, forest, and garden botany: a siiriple introduction to the com- mon plants of the United States east of the one hundredth merid-
ian, both wild and cultivated; revised and eatendecl by L. H. Bailey.
[New edition ] 519 pp. So New Poik, [1895.]
Insurance Company of North America.
John Crerar Library, Chicago.
Lakes ~iianual. 166 rip. 18" Chicago, [19O5. J
Libt of bibliographies of apecial siilbjects. 504 pp. 4". Chicago,
List o f cyclopedias awl dictioiiaries with n lizt of directories. 272
List of serial- in the public liliraries of Chicago aod Eranston, cor-
Nuuveau Larouest. illustrd; dictioitnaire universe1 encyclopCdique
7 v. Po. Paris, [1898-
1INJ2.
pp. 4". Chicap, 19IJ1.
rected to April, 1903. 11J1 pp. Chicago, l:N)3.
Larousse, [Pierre].
put)lie boils la direction de C'laudr Aug6 . . . 1904.1
Lippincott's New Gazetteer. A complete pronounciuy gazetteer or geographical dictionary of the
s, 2053 world . . . edited liy Aogelu Heilpriu and Louis Heilprin.
1)p. in. Philadelphia, 1905.
n. t. p. 18 pp.
8O. Eiliiiliargh, L1905.1 Reprinted from Scottish geographical maga-
zine.
Indexing: piiuciples, rules, and esanipleb. (Bulletin 94, Library
Material for wurse iu refertrnce study. I Bulletin 83, Library School
Selection o f cataloguer's refrrence l ~~o l i s in . . . State Library. (Bul-
Organic chetoistry; or, Clieiuirtry of the carhon compounds; edited
3d dmerican from
Mossman, Robert C. Scottish national Antarctic expedition; meteorolo~y.
v. 21, No. 8, Bugtist, 1905.
New York Stqte Library.
Schonl hulletin 19) pp. 465-5311. W . Albany, 1Y05.
)J l l l l e t i U 16) pp, 297-408. 8". Albany, 1303.
Ietiu 84, Bibliography llulletin 36) pp. 235-416.
1)y R. Anschiitz. translated by E. F. Smith.
8th (krnian edition. 2 v. 8". Philadrlphid, 1908.
Modern theory o f physical phenomena; radio-activity, ions, electrons;
authorized translation by Augastus Trowbridge. siii, 165 pp. 120.
New Pork, 1904.
On tlie treatment of climatoli~trical observations. n. t. v. 13 DD. 40.
80.
Rich'er, Victor von.
Righi, Augusto.
Biblii)grapliy, pp. 155 61.
Shaw, W[illiam] N[apier].
.- [ Eflinhu rgh 1, 1905. Rep riurecl f PO in Scottish meteorological soci-
ety. .Journal. ser. 3, v. 13 pp. 3-13.
Seasons in the Britibh Isles froin 1878. n. t. 1). 97 pp. 80. [London,]
1905. Reprinted from Royal statistical socicty. Journal. v. 68 pt.
2, June, 1905.
Societe Astronomique et Meteorologique, Port-au-Prince.
Strobel, Friedrich, comp. . . . Statnts. 5 pp. la0. Port-au-Prince, 1905.
A(1resal)uch der lebendeu physikw, mathematiker uncl astronoineu
x, 258. 80. . des in- unrl auslandes und der technischen hilfskriifte.
Leilizig, 1903.
Sutton, J. R. Iutlueuce of water-vapour upoil noutiirnal rdiation. (Royal Dubiiu
society Scientific proceediugs. New ser. v. 11, No. 3, August
1905.) pp. 13-33. Yo. Dihlin, 1305.
Switzerland. Meteorologische Central-anstalt.
Woodruff, Charles E[dward].
Annalrn. v. 40, 1903. v. p. fo. Zurich, [19U.5].
Effeots uf tropical light on white men. vii, 358 pp. 8". New York,
1905.
EXTRACTS.
erly. These observations mill not be printed in the MONTHLY
~VEATHER RErrEm, but the records frnin 01111' Weather Bureau
seisniozraphs and the special studies of Professor Marvin will
be thus printed for the information of all.
A GUIDE FOR THE OBSERVATION OF EARTHQUAKES.
1. IMPORTANCE OF TEE INVESTIGATION OF EARTHQUbKES.
Few branches of science have in the last few years received such a
great inqirtus a s tlie investigation of earthquakes. The modern investi-
gation of earthquakes dates from the time when, by the construdlon of
highly sensitive seismic instruments, it was made possible to register at any point of the surface of the earth 811 strong bhocks of the earth's
NOVEMBER, 1905. MONTHLY WEATHER REMEW. 487
crust. The perfection -which these instruments have lately reached
places u s In a position to trace around the earth the elastic waves pro-
ceeding from an earthquake with sufficiently strong intensity.
The number of stations equipped with such instruments is, however,
still very limited; t.heir distribution over the earth’s surface has not
been according to one uniform plan, lrut was dependent on necessary
conditions which were frequently by chance fulfilled in a less appropriate
place, but not in another more suitable one. The efforts of the Interna-
tional Seisinological Association, which was fonnded in the year 1903 a t
the Second International Seismological Conference a t Strassburg and t o which almost all civilized uations belong, will in the first place be
directed to creating a systeinatlcally arranged net of earthquake stations
and to establishing observations according to uniform priuuiples.
The records which the seismic iustrunients have SO far given hare
already thrown important light on the nature o f earthquakes, and
ahove all on the nature of the movement, on the Iihases of which
seismic disturbances are composed, on the direction from which most
earthquake waves come, on the speed with which seismic w a v ~s are
transmitted through and over the earth. But the principal valiir of
modern investigation of earthquakes consists i i i the fact that, by the use
of seismic instruments, i t supplies a means for obtaining a hetter wn-
ception, than was for a long time possible, of the state of the iuterior o f
the earth, which is entirely concealed from direct observation.
In the meanwhile, instrumental observation alone is not yet suffieirnt to solve the most important problems of earthquake iuvestipatiou. The
first question of seismology concerns the establishmeut of ‘‘ sc.isniicitg,”
i. e., of the seismic behavior of the whole earth.
I n former years the attempt. was made again and again to work out a
catalogue of all seismic disturbances, and to publish annual specifica-
tions of all known earthquake disturbances in the form of a chronicle.
The purpose thus aimed at was chiefly to discover the points o r districts
of the earth which are subject to shocks and from which the earthquake
waves radiate over more or less great. surfaces.
On account of the inadequacy and incompleteness oP the reports of
earthquakes in former years, i t wa.8 impossible even to do tolerable justice t o the flrst seismological problem. The manifold bonds, how-
ever, which to-day unite the nations to one another permit the holw that,
by all the nations of the earth working together to a conscious end, i t
will be possible to solve a question which was formerly impossible of
solution on account of international prejadic,es and jealousies.
In the first place i t is the intention to publish a seisinic atlas ou tho
basis of the material stored ill) in the existing CR talogues of earthquakes.
This atlas is to give a cartopraphical represc~~ta.tion of the esteut of
eart~hquakes and particularly of the position of the epicenters.
The second pi-oblein of seismology is to tleteriniue the relation of
the position of the epicenters to the geological constitution of the rlis-
tricts in question, whether it is a temporary or a permanent relation, whether earthquakes displace the point of emergence, whether the
energy of seismic activity is subject to changes in point of time and
place, and lastly whether the frequency of earthquakes is perioilic or not.
In the former state of earthquake investigation a solution of all these
questions was not to be thought of, and even now many years of obser- vation and a collection, as complete as possible, of earth(1uake d a h
will be necessary if we wish to advance in this respect, for it is just in
this second problem that instrumental observation alone does not suffive;
here, on account of the personal observation necessary, science inofit
fall back upon the voluntary cooperation of all educated people. From
the records of the seismic instruments we can only gather the nature of
the movement at the place of observation itselP; we learn nothing about
the extent and shape of the shaken area, about the different iudicatious
of intensity within the shaken district, or a1)out the manifold accompany-
ing phenomena.
Instrumental records and personal observations thus form a nxes- sary complement of each other. If earthquake observation and investi-
gation is henceforth carried on everywhere in this modern sense, seia-
mology itself will have the first and greatest benefit. But there will also be a general, direct, practical profit from it. When the nature of
earthquake waves has been niore exactly investigated, when the corre-
lation of the various manifestations of seismic power with the local
conditions, which perhaps produce such manifestations, bec:omes better
known. when we hare established the chief epicenters and their appur-
tenant shaken districts, it will be possible, if not to indicate the earth-
quakes in advance, at least to find ways and meaus whereby the most destructive effects of the earthquakes can be obviated and life and
property be saved.
It is the privilege of all educated people of the earth to collaborate in
this great and difecult task.
The following remarks aim to present in a generally COmpreh01lSible
manner ti10 principal earthquake phenomena the exact observation of
which is most important, thereby enabling everybody who is interested
t o collaborate in the service of science and for the good of mankind.
Thereto are added instructions for the answering of questions, if i t
should be necessary, and the filling’up of tlie accompanying question
cards. I n conclusion there is given a question card which may serve as
a model, the data of which are taken from an actual case.
65-3
2. TEE MOST IBIIPORTANT EARTRQUAhE PHENOBlENA.
Earthquake is the name given t o all those shocks, whether they can
be perceived by the human senses or not, which owe their origin to any
disturbance of equilibrium in the earth’s mass, and which are transmitted,
in the shape of spherical waves, as elastic vibratious, i. e., as waves of
compression ant1 rarefaction, through the medium of the e a r t h s body
from their place o f origin. If the place at which the earthquake waves
leave the earth’s crust lies a t the bottom of the sea, and if the spherical
waves are transmitted across the body of the water to the level of the
sea, i t is called a submarine earthquake, or seaquake.
(a ) The shock of nib earthquake.
The periodically alternating compression and rarefaction of the ma-
terial of the earth’s crust which are caused by the disturbances of equi-
librium in tlie bowels of the earth, form the waves o f compression and
rarefaction, the movement of which is divided into a vertical and a hori-
zontal component. On account of the immense energy of tension and inorenient which is contained in the elastic waves, earthquakes show
thrmselves in sudden shocks of different iuteusity.
Iuimediately above the subterranean earthquake seat and also in the
neighborhood o f the elbicenter the vertical component preponderates.
To human perceptmion the shock oP an earthlluake makes itself felt as a shock from below i n a n upward direotiou. As the distance from the
epicenter increases, the vertical coinponent diminishes more and more
u u t i l a t last only the horizontal coml)onent of the motion remains. In this case the sepmrte parts of the earth move to and fro horizontally
and proiluce the sensation of an undulating motion. Thus the prepon-
derauue of one or the other coinponrnt of the inntion can be considered
as a criterion for the est,imation of the relative distance of the observer
from the epicenter.
(b ) iVutnber ntd dtircrtion of the shocks.
I u many nases the earttiqriake consists of one single shock and lasts
only a fraction of a sel:onil, and the most terrible destruction is the work
tnP an instant. Io most cases, however, a whole series of shocks of dif-
fereut force ftbllow one anotherat shorter or longer intervals. Generally, weak shocks conic first : then the principal shock occurs, and the end of
the shock is composed of vibrations becoming gradually weaker and
weaker. The seismic disturbance may, however, begin a t once with the
btrongest s1it)ck and then die away with weaker tremblings. In this case the whole series of shocks is desiguated the earthiloake, and the
duration of the earth~luitke comprises the time, inclusive of the intervals,
which elapses between its flrst appearaucn and the last vibration. The durat,ioii o f an earth(1uake is generally overestimated, because the ob-
servers are surprised by the sudden appearauce of the phenomenon, and
usually remain excited for a time after its end before they come to their
0
When the number of shocl~s which follow one another in a compara-
tively short time is very large, they are called a swarm of earthquakes.
The space o f time over which the shocks extend may comprise several
days, even we11ks and months. If one and the same district is repeatedly
visitell by suc:h earth(luakes, i t is called a regular earthquake district.
senses ant1 are able to realize what has 1i:Lppeuetl.
((a J The afttlr shocks.
A very violent earthquake is frequently followed by a large numberof
after shocks. The stronger the principal shock and the smaller the
shaken area, the more nuinerous the after shockfi. The time over which
the after shocks extend may comprise several years. With the increase
of time, however, the frequency of the after shncks diminishes. The dis-
trict in which the after shocks make themselves felt does not always
c(1rrespontl entirely with that of the principal quake ; the epicenters of
the after shocks often OCI’UP at different places within the principal
shaken areas. Observers are in the habit of paying no attention to the after shocks,
because they attach no importance to them in comparison with the
1)rincipal shook. Iu view of this, i t must be emphasized that, from t.he
standpoint of earthquake investigation, the same importance attaches to the after shoc,ks as to the moat violent shock. Accordingly, every
aft,er shock must, with regaril to the t.ime, duration, and intensity, be noted with the same care as the first s h o c ~. In one respect the obser-
vation of the after shocks is even inore important than that of many other seismic phenomena. In all probability the appearance of the
after shocks is dependent on the changes OP the air pressure on the
shaken area and on the attractive power of the moon and sun. The
after shwks are thus best qualified to throw light on the question of the
periodicity of earthquakes.
(d ) Intemity of ea&qualiea.
The form of a shock is usually given according to a conventional scale. The best known aud most. used is the earthquake intensity scale which
De Rossi and Fore1 devised.
I. Microseismic motion, recorded only by seismic instruments.
11. Shock registered by seismographs, observed by a small number of
111. Shock observed by several persons in a state of repose; strong
It distinguishes ten degrees:
observers who are in a state of repose.
enough for duration or direction t o be estimated.
488 MONTHLY WEATHER REVIEW. NOVEMBER, 1905
IV. Shock observed by persons in activity; shaklng of moveable ob-
jects (windows, doors), cracking of the floor.
V. Shock generally remarked by the whole population; shaking of
objects, furniture, beds, isolated ringing of house bells.
VI. General awakening of those asleep: general ringing of house
bells; oscillation of hanging lamps; stopping of watches; visible oscil-
lation of trees; isolated cases of persons quitting their houses in terror.
VII. Overturning of moveable objects, loosening of plaster on the ceil-
ing and walls, ringing of church bells, general terror, hut no damage to
buildings.
VIII. Falling of chimneys, formation of cracks in the walls of houses.
IX. Partial or entire demolition of certain 1:iuildings.
S . Great catastrophe, ruins, fissures in the eart.h’s c,rust, land slips.
In generalone may make the observation that earthquakes are stronger in the surface strata than in the depths of the earth. The effect oP an
earthquake depends in a high degree on the nature of the material of the earth’scrust concerned. It can thus happen that one and the same
shock will be felt very differently under otherwise similar conditions in
places which are situated near to one anot.her.
(e ) Effects of earthqualm on tile earth’s surfuce.
Faults, cracks, fissures, which run off in the most manifold directions,
intersect and thus cut up the land into blocks, belong t o the very transi- tory, because superflcial, changes of the earth’s surface. A s a rule they
close up again of their own accord. If the fissure reach into the under-
ground water, springs and small drains are affected.
There frequently occur round holes, which resemble an inverted
cone and which throw forth slimy water when a violent earthquake
takes place. I n this case sand cones, which have the appearance oP
craters, are formed. More extensive transformations of the earth’s surface give rise to clefts
which by a greater extension in length, breadth, and depth may hecome
real faults and which may be combined with vertical and horizontal (lis-
placements. Movements of masses, such as landslips, mountainslips, and subsi-
dences take place with earthquakes only when the soil is composed of
loose or water-sodden material. Particular consideration should be given to the movements that are
manifested during earthquakes by water, whether of lakes or of the
ocean. In the lakes the water masses begin to oscillate or else waves arise on the surface. Flowing water may be made stagnant. The most
remarkable, however, are the events which may be observed in the sea
during coast earthquakes, namely, the so-called earthquake tidal waves.
How the sea water behaves during a coastquake, whether i t first
withdraws from the bank or whether a rise of the water first takes
place, is not yet established.
e The damage to buildings is of particular importance for the estimation of the direct.ion of transmission and of the int.ensity of the eai-th(luake
waves. Here, however, i t must be remembered that the stability of
the buildings in relation to the earthquakes depend; principally on the
material used in the building and on the construction. If in one case
old decayed huts fall in, and in another case massive dwelling houses
only show cracks in the walls, it is not immediately to be deduced that
the violence d t,he quake in the first instance reached a higher degree
than in the second. According to A. Faidiga, the principal forms of destruction observed in
buildings are as follows:
1. Complete or nearly complete ruin of the buildings.
2. Falling in of the gable walls, with preservation of the side walls and
of the superstructure of the roof.
3. Preservation of the gable walls with a partial falling in of the side
walls with the superstructure of the roo!.
4. Destruction of certain corners, generally the upper ones, and of
whole ledges of the building. 5. Falling in of the whole wallwork, together with a sinking of the
superfitructure of the root The destruction of buildings is due, in t.he Erst place, to the fact that
all thelr parts do not yield equally in the direction o f the wave. IP the
extension of length coincides with the direction of the shock, cracks will
arise lengthwise. If the wall stands perpendicular to the direction of
the shock, oblique cracks will be formed, and these lead more easily to
collapse. If the wall is presented obliquely to the earthquake waves, the direction and size of the cracks will follow the law of the composition
and resolution of forces; here, i t is t,rue, irregularities in material and
construction have a dotermining influence.
3. DETERMINATION OF THE POSITION OF THE EPICENTER.
Apart from the knowledge of the nat.ure of seismic phenomena in
themselves, the aim of earthquake investigation is above all directed to determining the position of the epiceuter in every single case. For that
it is necessary to have numerous individual observations, in as many
different places as possible, of the beginning of the shock, its strength, direction, and effect, for every individual place of observation. For
this, those communications which flrmly establish the nonappearance of
the whole quake or of isolated phenomena are of value. Such negative
statements serve partly for the understanding of the inequalities of the
shock, and partly to determine the gradual diminution of individual
phenomena in its expansion, and also to determine as exactly as possible
the limits of it.s expansion.
The three elements, intensity, direction, and time of the shock, which
are necessary for the establishment of the epicenter, belong, i t is
acknowledged, to those which i t is niost difficult to determine in every
earthquake. Thus the greatest care should be given to the observation
ne these three elements, and only reliable statements should be made.
Experience tells u s that, especially in the determination of the time,
deviations of several minutes from the true time occur. The observa-
tion of the moment of the shock is uot always exact even in telegraph
offices and railway stations, because the necessary care in setting the
clock to the official time is not everywhere used. The inexactness is
still greater when i t is a question of ordinary house clocks or pocket
watches, and even the later comparison of the pocket watch with a clock
showing standard time often gives faulty results in consequence of the
uncontrolled timekeeping o f the watch.
4. PHENOMENA ACCOBlPANTINCi EARTHQUAKE?.
Among the phenomena which among others follow in the track of
earthquakes, the most important is the sound phenomenon. Most fre-
quently these so-called earthquake sounds imluediately precede the prin-
cipal shock. But cases have also occurrecl in which they take place siniultaneously with i t and still continue after the end of the quake.
The nature of earthquake sound is variously given as roaring, whistling,
howling, rolling, thunder, cracking, bellowing, etc. On the whole, two
principal groups may be distinguished, namely. sounds long drawn out
like the rolling of thunder, or shortly hroken off, like the explosion of a
mine.
The force of the noise stands i n no relation to the force of the shock; feeble
shocks may be accompanied by a very loud noise and rice versa. In
inany places noises are heard without any accompanying shock being
felt. These so-called ground claps have special names in different
countries.
The following scale is proposed by J. Knett for estimating the force of
the detonations:
1. Detonation of the very smallest force; only dimly audihle amid the
greatest quiet arid by laying the ear upon the ground.
3. Detonation of small force; amid the great.est quiet aud absence
of wind dist.inctly audible in the air; more distinctly by listening on the
3. Detonation of medium force; a noise dist,iuctly antlible in the open
air even without complete quiet; distinctly audible in a iluiet, closed
room.
4. Detonation of great force; strong terrifying noise.
5. Detunation of the greatest force; violent, thunder-like; similar to
the reibort of not far distant cannon; general terror among the population.
Light and fire phenoineua are also often reported as accompanying
earth(1uakes. llut i t is not impossible that this iuay Ile a delusion.
Earthquake sounds occur in both earthquakes and seaquakes.
gr0UUd.
5. INSTHUCTIONS FOR FILLING UP THE QtIE5TION C!ARDS.
(a‘) One is recommended to fill up the card inmediately after the event,
when one is still under a fresh impression of it.
(b ) A s a rule, a separate card is to be used for each separate earth-
quake. Eveu when several after shocks follow t.he principal shock on the same day, a special card should be used for each separate distinct
shock. (c ) Information which has been obtained later from other persons for
the completion of one’s own observations is to he written on special
cards. (d ) For the sake of certainty, the day of the meek shnulcl be added to
the date of the earthquake.
(e’) In giving the time, i t must be added whether i t is local mean time
nr standard time.
Whenever possilde, one should give not only the time of the beginning
of the quake, but also that oP the principal shock and of the end of the
quake.
It is not sufficient for the observer to state at what time the earth- quake took place according to his watch; he should as soon as possible
compare his watch with a well regulated clock (post office, telegraph
office, or railway clockj. If a railway clock is used, one must be guided
by the clock useil for the inner service, as in many station8 the outside
clock intended for the use of the public is wrong by five minutes.
The watch correction is, however, not to be applied to the time state-
ment, but is to be entered separately. If one’s own watch is flve min-
utes fast in comparison with the standard clock, one places a + (slgn of
plus,) before the number of minutes and seconds, or in the reverse case a
- (minus sign). Thus, for example: 5b 4303 308 (+ 5m).
Even if the observer possess a good timekeepiug watch, his time
statement is subject to more or less inaccuracy, because according to
the circumstances, especially at night, a certain time elapses before one
is able to read the time. On this account at least the limits should be
given within which the phenomen0n has been observed.
(f) It is of value to know how much of the time observed is taken up
with a sound preceding, simultaneous with, or succeeding the shock.
NOVEMBER, 1906. MONTHLY WEATHER REVIEW. 489
(g) Since the direction of shock and direction of propagation do not
always coincide, particular attention must be paid to the direction in
which unsupported objects are overturned, or in which direction furni-
ture is displaced, or in which direction hanging lamps or fluids oscillate.
If clocks stop or pictures knock against the wall, the bearings of the
walls should be given.
(h) With regard to the nature of the shock, i t should be observed
whether only one or several consecutive shocks were felt, and whether
a jerky or wave-like movement or only a trembling of the ground was
felt.
Other remarks concerning the c,oiuposition oP the soil, etc., must be
left to the discretion of the observers.
6. QUESTION CARD.
Earthquake.. . . . . . . . . . . . . . .(day oP the week). . . . . . . . . . . . . . . .19
Place.
A t what time? h m 8 (local mean time) (standard time)
A. M. or P. M.? Where was the observer?
In the open air?
In a house?
Iu which story?
Number, duration of the shocks?
Direction of the shocks?
What effect had the earthquake?
Earthquake sounds?
Behavior of springs, wells, etc.
Other remarks.
Address of the observer.
Earthquake. Monday, January 19, 1889.
Place. Ascoli Piceno.
A t what time: a. m. M. T. Rome. Where was the observer'!
In which story? - Number and duration of the shocks : One shock; two seconds.
Direction oP the shocks: E. --W. jerky, VIII.
What effect had the earthquake?
Earthquake sounds. -
Behavior of wells, springs.
~
Other remarks: Church bells begau to ring.
7. SAMPLE OF EARTHQUAKE NOTICE.
In the open air.
Cracks in the walls.
General flight from the
houses.
Data desired relative to Reaquakes.
1. Position of the ship at the time of the earthquake.
making?
2. Place of the observer.
3. Time of seaquake.
4. Kind of motion.
What course was the ship sailing and how many knots was she
Was the seaquake felt by the observer below the deck or on deck?
bt what moment was the seaquake perceived?
(a) Merely trembling or shaking or shocks?
(b) Was the motion vertical or undulatory?
(e) Were the shocks preceded by a trembling motion or were they
(d) What is the motion to be compared to, and what impression
5. Direction of the propagation of the motion.
Was the direction of the motion from bow to stern or vice versa,
or can a certain direction by the compass be stated?
6. The intensity of the earthquake is to be given in degrees of the
following scale:
I. Quite slight trembling, more like a noise; mostly heard
only below deck (111 of the Rossi-Fore1 scale).
11. Slight trembling, by which a sleeping crew might be
awakened (IV of the Rossi-Fore1 scale!.
111. Trembling of the whole ship, such as might be caused b j
large casks being rolled across the deck (,IV oP the Rossi-
Ford scale).
IV. Moderate shaking like that felt when the anchor cable is
quickly slipped (IV of the Rossi-Fore1 scale).
V. Rather a strong shaking, as if the ship were scraping on
rough ground (IV of the Rossi-Fore1 scale).
VI. Strong shaking by which light things may be moved ; the
wheel jerks in the hands of the steersman (,V and V I of
the Rossi-Fore1 scale).
VII. Very strong shaking by shocks so as t o make the timber
work crack and to render i t impossible to keep on one's
feet (VI1 of the Rossi-Fore1 scale).
VIII. Very strong shaking by shocks; masts and rigging as well
as heavy things on deck are shaken (VIII of the Bossi-
Forel scale).
I S . Exceedingly strong shaking by shocks ; the ship is thrown
on its side, slackens, or is stopped (IX of the Rossi-
Forel scale).
followed by such a motion?
did i t make upon the observer?
S. Destructive effect; people are thrown down upon deck, the joints of the deck burst, the ship becomes leaky (X
of the Rossi-Fore1 scale).
Did the intensity vary with the single shocks or durlng
the whole phenomenon?
(a) What was the duration of the shaking itself, apart from the
(b) Were there siugle phases to be distinguished in the phe-
(a) Was a noiw heard, and what was i t to be compared to?
(b) Did the noise precede the shaking, was i t at the same time,
(a) What was the btate oP the sea surface before the seaquake
(h) Did i t remain in the same conllition, or did any changes take
(c) Was a single peculiarly hfgh wave observed or a succession
(d ) Was the level of the sea, although smooth, raised, or did i t
Did a sudden variation of the needle take place during the sea-
(a) Was the temperature of the sea water higher after the sea-
I b) What was the atmospheric pressure?
(a) Were any other ships near a t the time of the seaquake, and
(b) Was the seaquake perceived by them or not?
13. Earthquake and seaquake.
In rase the ship is lying in a harbor, inquiries are to be made on
land concerning:
(a) The beginning.
(b) The intensity.
(c) TI13 duration of the earthquake.
7. Duration of the seaquake.
noise, I J ~ which i t was accompanied?
nomenon?
8. Sounrls.
or did i t follow it?
9. See surface phenomena.
took place?
place during the seaquake?
oP them ( height and length)?
lmbble like boiling water?
10. The compass.
11. Meteorological phenomena.
quake ?
quake than i t was before?
12. Extension of the seaquake.
if so, at wnat distance?
Wiat difference was there between the earthquake and the
seaquake as to these three points?
14. Condition o f the sea in the harbor during an earthquake and a sea-
quake.
(a) Had the shaking any influence upou the water in the harbor?
(b) Dill any breakers come in at the inument of the shaking or
immediately after it, and if sv, how many, how high, a t
what intervals?
(c) Did the ship drag her anchor and were any currents percep-
tihle. (d) Did a so-called earthquake tidal wave take place, and if so,
how long after the beginning of the earthquake; how many
waves, what height, at what intervals?
INDIAN SUMMER.
A correspondent writes to inquire " the time and duration
of Indian summer '' for the latitude of Washington, D. C.
Indian summer is an extremely indefinite season as to its
date nncl its character. There has never been any determina-
tion of its average date and duration so far as we know. It
is often described as a warm, dry, hazy period after the first
severe frost in autumn, but i t often fails to come at all.
The date of the first severe frost a t Washington has ranged,
since 1871, from October 2 to November 16, and at Baltimore,
during the same period, the range has been between October
G and December 6. This might serve to fix the earliest pos-
sible date for the beginning of Indian sumiuer.
The paper by Nr. Albert Matthews on '' The Term Indian
Siiiumer," which appeared in the MowHLT WEATHER REVIEW
for 1902 on pages 19 and 69, is one of the most complete and
exhaustive discussions of the subject and its perusal is recom
mended to those who take an interest in this subject.
A LECTURE ON SNOW CRYSTALS.
Our esteemed correspondent, Mr. W. A. Bentley, of Jericho,
Vt., whose beautiful photomicrographs of SUON crystals are
known the world over, devotes his whole thought to the prose-
cution of this work. Being unable to leave Jericho, owing to