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TRAVANCORE STATE MANUAL Volume One
V. NAGAM AIYA
Dewan Peishcar, Travancore kingdom
2. Climate, Rainfall and Meteorology

Climate Seasons

Temperature Diurnal variation

Annual variation Rainfall

Annual variation Periods of deficient rainfall

Wind Variation of wind velocity

Storms Earthquakes

 

Sing a hymn, pleasing to Varuna the king. He sent cool breezes through the woods, put mettle in the steed (the sun), milk in the kine (clouds), wisdom in the heart, fire in the waters, lightning in the clouds, placed the sun in the heavens, the Soma on the mountains. — He upset the cloud-barrel and let its waters flow on Heaven, Air, and Earth, wetting the ground and the crops. — He wets both Earth and Heaven, and soon as he wishes for those kine’s milk, the mountains are wrapt in thunder-clouds and the strongest walkers are tired.” (Rig Veda)


 

Climate


A warm humidity is one of the special features of the climate of Travancore. Small as the country is, its high mountain ranges, its valleys and plains and its coast-line greatly influence the atmospheric condition. The temperature varies according to the height of the locality above the level of the sea. But the most noticeable variations are common only in the mountains. The climate of the plains is much more constant and is subject to comparatively few irregularities. The thermometer rarely shows a higher reading than 90° and even in the coldest season it never falls below 70°. This uniformity of temperature is explained to be due to (1) the superheated condition of the surface soil, (2) the cool sea-breezes and the abundance of rain throughout more than half of the year and (3) the process of evaporation.


In the whole of Malabar and Travancore, there is no thick layer of cool earth on the surface capable of quickly absorbing the sun’s rays, as in the Temperate Zone. Hence the surface soil becomes very heated and is constantly radiating its heat day and night, and consequently a uniform high temperature is maintained.


The cool sea-breezes, always saturated with moisture, blow steadily and regularly every day during the hot weather. These, combined with the abundance of rain that falls in the country, moderate the intensity of the heat and maintain a uniform temperature.


In the process of evaporation a large amount of heat becomes latent. This goes on in the hours of the hottest sunshine. As the country is well equipped with back-waters and rivers and as it is on the sea-board, evaporation plays an important part in moderating the heat and reducing the temperature.


The hills present every degree of temperature from the fever heat at their base to near the freezing point upon the summit. At the foot of the hills and in places beyond the influence of the sea-breeze, the thermometer rises 5° or 6° higher. On the hills, the temperature varies with the elevation. In the Periyar valley near Peermade, the country being completely shut up by high land, the extreme range of temperature is very great, varying from little more than 45° to over 90°. As we go higher, the air is naturally much cooler. The Kanni Elam hills, one of the divisions of the Cardamom Hills, are about 3,000 to 3,500 feet high and are within the influence of the sea-breeze and consequently pretty free from bad fevers. But the Makaram Elam hills, though higher, are during some months very unhealthy. From July to January they are healthy and the temperature is low; but from the end of February or early in March, fevers of the worst type prevail and continue till June.


On the High Ranges the thermometer ranges from 45° to 60° in March and April and between 29° to 60° in November, December and January. The meteorological effects of the whole of India, if not of the whole world, are thus presented to us in Travancore in a small compass. On some of the peaks we have the pinching cold of the northern regions of Europe. Lower down on an elevation of between three and four thousand feet (the Ashamboo or Peermade Range for instance, one meets with the bracing temperature of England. The genial warmth of an Italian sun with its clear and cloudless sky is experienced all over the country for a few weeks after the cessation of the monsoons.


From January to May there is intense heat which in some Taluqs present the aspect of a true equatorial region and epidemics rage with virulence. The three months after the partial cessation of the rains are the most agreeable and salubrious, “the air being cool and refreshing and the face of the country clothed with a luxuriant verdure”. The dewy season is not agreeable to the working classes. On the whole, the climate of Travancore is enervating, depressing the nervous system and retarding the recovery of strength when it has been prostrated by illness.




Seasons


Our ancient Sanskrit writers have divided the year into six seasons or Rithus, each comprising a period of two months. Of these the first, Vasanta Rithu or Spring, is the season of mirth and gaiety and begins in March. “The mango is then covered with fragrant blossoms of which Manmatha the Indian Cupid makes his shafts and the landscape is gay with the beautiful and the sweet-scented flowers of the kakke or Indian laburnum. The southerly breezes that blow daring the night are the voluptuous zephyrs of this vernal season.


The next two months are designated Grishma Rithu or the Summer season. Varsha Rithu or the rainy season comes next. The South-west monsoon blows steadily during this period. During the next season, Sarad Rithu or Autumn, the fruits of the earth ripen. This season closes with the change of the monsoon. The Hemanta Rithu or Winter next sets in with chilly mornings and bright sunny days. The Sisira Rithu or cold season closes the circle of the year.


The year in Travancore may, however, be divided into four seasons, viz. , the Dry or dewy season, the Hot weather, the South-west monsoon proper or wet season and the Retreating South-west monsoon period, based on the mean data of the meteorological elements given in the following tables, I and II, obtained from the Trivandrum Observatory.



The following table gives means for the four seasons corresponding to the data of Table I.




The dry season lasts from December to February, and is characterised by moderate humidity and cloud, and by very light rain and absence of thunderstorms. This is the dewy season or the cold weather, but referred to here as the dry season on account of the fact that the air contains the least aqueous vapour in this season.


The hot weather lasts from March to May, it’s most prominent features being moderately high temperature, occasional rain (increasing in quantity with the advance of the season) and frequent thunder-storms. Throughout this season, there is an intense and oppressive heat which is very intolerable in March and April. No doubt the season is slightly relieved by a few showers; but still the continued heat is insufferable and some of the places present the aspect of a true equatorial region from which it is not far distant. The country of Nanjanad though fully exposed to the severity of the suns heat, is relieved of much of its intensity by the strong sea-breezes which sweep across the plains. During these months, in the lower hills, the violence of the heat is extreme. As we recede from the coast, the country becomes le«s healthy. During this and the previous season, fever, generally in the hills and in the valleys, and some of the epidemics, especially small-pox and cholera, break out occasionally with very great virulence. The borders of the lakes, however, always afford an agreeable climate.


The South-west monsoon proper or wet season continues from June to September, and characterised by clouded skies, high humidity, copious rain and absence of thunderstorms. Sometimes the monsoon commences towards the end of May and the regular rains are ushered in by thunder and lightning. Till the end of August the rains are very heavy and by September the rainfall becomes much lighter.


The retreating South-west monsoon period includes the months of October and November. Its chief feature is rain diminishing in amount with the advance of the season. The rains are, as a rule, preceded by thunder-storms of greater or less intensity. But the greater part of the rain registered in Travancore is brought by the S. W. monsoon. The amount varies considerably, being least in South Travancore, but gradually increasing along the sea-board to its northern limit. Towards the end of October, the N. E. monsoon begins and all through the month of November, a heavy shower is experienced in the afternoons though the mornings are generally fine.


By the beginning of December, the rains become less frequent and the country begins to dry up; by the end of December, the dry weather is fairly begun. Dewfall begins at nights in November and lasts till February. The sudden changes in the temperature of this season, from intense heat in the day to excessive cold in the night, often generate and foster the development of the epidemics, especially cholera. The land winds that prevail in the months of November, December and January produce many unpleasant ailments such as rheumatism, coughs, disordered stomach and pains all over the body. Jungle fever prevails near the foot of the hills; the moist heat at this part of the year is very depressing and is the cause of the above mentioned disorders.


Temperature*


Diurnal variation. In Trivandrum, the mean epoch of minimum temperature occurs at 4-51 a. m. on the average of the whole year. Thence the temperature goes on increasing till it agrees exactly with the mean temperature of the day at 8-16 A.M. and attains its maximum at 1-34 P.M. Thenceforward the temperature goes on decreasing till it is once more identical with the mean of day at 6-58 P. M. and finally reaches its minimum again at 4-61 A.M. The following table exhibits the diurnal oscillation of temperature at Trivandrum during the four seasons and for the whole year —


NOTEs: * For the account of temperature, rainfall, winds, storms and earthquakes, I am indebted to Mr. Velu Pillai, Head Assistant of the Trivandrum Observatory




Annual variation: Temperature increases [with fair regularity from the middle of December to the beginning of April. It then falls, at first very slowly in April and May and then slightly more rapidly in June and the first half of July, to a secondary minimum in July (76.3° on the 13th, differing only by 0.08° from the absolute minimum on the 16th and 17th of December.


During the remainder of the year, the mean daily temperature ranges irregularly within narrow limits (between 76.2° and 77.5°), indicating that the normal seasonal changes of temperature of this period are very small compared with the variations due to local and occasional actions or causes, such as rainfall &c. The chief feature of the progression of temperature during this period, however, appears to be that it increases slightly and somewhat irregularly from the 13th of July (76.3°) to the 28th of September (77.5°) and thence decreases with approximate regularity to the 15th of December. The following table gives, in brief, data of the chief maximum and minimum epochs of the variation of temperature during the year.





It may be observed that the average or normal daily temperature is above the mean of the year for only 115 days, i.e., from the I5th of February to the 9th of June and is below it during the remainder of the year. The mean diurnal range of temperature for the 12 months and for the year is given below: —




Table VI gives the mean actual daily and monthly temperatures at Trivandrum derived from the series of observations taken during the period 1856-1864, and Table VII gives the mean hourly temperatures for each month and for the whole year.








The following table gives the data for the diurnal variation of the amount of vapour present in the air and also for the diurnal variation of humidity for each of the four seasons of the year and the average for the year in Trivandrum:





Rainfall


The territorial distribution of rainfall in Travancore exhibits two well-defined characteristics. One is the gradual diminution of rainfall from Parur to Cape Comorin, and the other the gradual increase of the fall proceeding from the coast towards the mountains. Besides, it is also true that up to a certain height the rainfall over the mountains gradually increases in amount. Considering the variation of the mean annual rainfall, Travancore may be divided into three narrow belts, namely, (1) the littoral or the lowland, (2) the submontane or the central and (3) the mountainous or the upland belt. The littoral belt has an average annual rainfall of 67.6 inches, the submontane 92.9 inches and the mountainous or the upland 110.1 inches. Thus it is seen that the amount of the precipitation of vapour increases from the coast towards the ghauts, the weight of the fall over the mountains being a little less than twice the weight of the fall near the coast.





The S. W. monsoon winds blowing over the Arabian sea take a north-westerly bend before they come into contact with the coast lands of Malabar and are felt as north-north-westerly to west-north-westerly winds in Travancore. The direction of the wind partly depends upon the trend of the coast-line, and the rainfall will depend on the angle which the monsoon currents make with the ghauts. It is not improbable that the maximum of precipitation occurs at the place of incidence of the monsoon current on the Malabar coast, which may vary in position from year to year. The law of the variation of rainfall along the coast is one of gradual decrease from this point, as the cm-rent reaches nearer and nearer to the Cape. A slight variation from this rule resulting in a diminution of the amount of rainfall at Shertallay, Kartikapalli and Karunagapalli is also perceptible, but it is difficult to offer an explanation for this diminution.


The mean annual rainfall at some important stations on the coast is given below:—




The Kottayam Division receives three times as much rain as the Padmanabhapuram Division, while Trivandrum has nearly 71% of what Quilon receives. Though the most favoured locality in Travancore as regards rainfall is apparently the Cardamom Hills, data are wanting to corroborate the belief. Of individual stations, Peermade has the greatest rainfall averaging to 198.4 inches annually. Todupuzha has the next greatest amount, viz., 145.2 inches. The least recorded fall is seen at Aramboly where it averages to 29.1 inches.






Annual variation


The annual variation of rainfall in Travancore follows a regular curve that has two maxima and two minima. The absolute maximum and minimum occur in June and January respectively, while the secondary maximum and minimum fall respectively in October and September. The least amount of rainfall is received in the month of January. Precipitation then goes on moderately increasing till the commencement of the S. W. monsoon, which takes place generally about the last week of May. June is preeminently the month of maximum rainfall throughout Travancore. Then a slight diminution takes place in the amount of the rainfall received in the several stations during the months of July and August, and the secondary minimum is arrived at in the month of September. There is a sudden increase in the amount of rainfall in the month of October. This rain is locally known as Thulavarsham. The fall then decreases slowly in the month of November and rapidly through December and January, which last is the driest month of the year. More than 87% of the annual rainfall is received during the prevalence of the S. W. monsoon, viz., from May to November.


Periods of deficient rainfall


As for periods of deficient rainfall, it is on record that the year 1860 was a year of famine in South Travancore. The rainfalls in Trivandrum for 1855 and 1870 also indicate years of scarcity. Beyond this, it is impossible to accurately determine the years of deficient rainfall before 1885, as it was only from that year that an extensive system of rainfall observations was begun. During the year 1881, however, rainfall records were received from 13 stations, and the amount of rainfall in all of them was far below the normal, the actual amount in one of them being 64% less than the normal. In 1880 and 1890 the fall was below the normal at 27 and 30 stations respectively out of the 86 stations at which rainfall was gauged. At the stations at which the rainfall was below the normal, the deficiency was 28% of the normal in 1886 and 23% of the normal in 1890. In 1894 and 1895 the rainfall was below the normal by 518.25 and 565.37 inches respectively i.e., by 17.0% and 18.6% of the normal. Out of the 36 stations, 30 stations in 1894 and 31 stations in 1895 had rain below the normal. In the years 1892 and 1893, a considerable deficiency in the amount of rainfall seems to have taken place in the Padmanabhapuram Division alone. The actual amounts received were 65.6% of the normal in 1892 and 63.3% in 1893. Thus it may be inferred with a fair degree of accuracy that the years 1886 and 1890 were years of deficient rainfall throughout Travancore. The biennial period of 1894 and 1895 must also have been more than usually dry throughout Travancore. The years 1892 and 1893 seem to be years of drought in South Travancore though the intensity of the drought may have been feeble.


A table giving the mean monthly and annual rainfall at 36 stations in Travancore is given below:




Wind. About the general character of the air movement at Trivandrum, Mr. J. Elliot writes*


NOTEs: * Indian Meterological Memoirs; Part I, Vol. X


‘’During the period from November to April when north-east winds generally obtain in the south and centre of the Bay of Bengal and the air movement is continued across the Deccan, Mysore and South Madras as north-easterly to easterly winds, Trivandrum is sheltered by the high Travancore hills from these winds. The air motion at Trivandrum during this period consists of an alternating movement between land and sea (i.e., land and sea-breezes) and of a feeble general movement from directions between north and west common to the Konkan and Malabar coasts at this period. The direction of the movement is apparently determined in part at least by the trend of the coast.


“During the remainder of the year, from about the middle of May to November, South-west monsoon winds of greater or less intensity prevail in the Arabian sea. They usually set in on the Travancore coast in the last week of May. They have their greatest extension and also the greatest intensity in the months of July and August. They begin to fall off in strength in September and continue to decrease in intensity in the south of the Arabian Sea in October and November, but withdraw gradually during these months from the north and centre of the sea area, being replaced by light variable winds. During the period of the full extension of the South-west monsoon over the north of the Arabian sea into upper India in July and August, the current in the south-east between the Laccadives and Maladives and the Malabar coast not only falls off to some extent, but in the lower strata instead of rising directly and surmounting the Travancore hills it tends to be deflected towards the south by these hills and to pass south-eastwards along the coast and join that part of the current which passes to the south of Ceylon and enters the Bay. There is hence a slight northerly shift of the winds on the Malabar coast from the beginning to the middle of the South -West monsoon.”


Variation of wind velocity.


The annual variation in the strength of the winds in the south and. centre of the Arabian sea is reflected in the winds at Trivandrum. The air movement is least at Trivandrum in December, or at the end of the S. W. monsoon. It increases slightly during the next three months and rapidly from April to July and is absolutely greatest in August. It falls off very rapidly in October and November attaining the minimum in December.


The diurnal variation of velocity differs considerably in character at different seasons of the year. From November to April it is determined by the alternating movement of the sea and land breezes. There are hence during this period two maxima and two minima, the former corresponding with the greatest intensity of the land and sea breezes, and the latter with the average of the shift from one to the other which, of course, varies considerably from day to day. The day maximum of the sea-breeze is very strongly exhibited as is also the evening minimum. The morning maximum and minimum of the land-breeze are, as might be expected, less marked than the corresponding phases of the sea-breeze, but are clearly shown.


They are most pronounced in December, January and February; and it is hence in these months that the land and sea breezes are probably most prominent and form the chief feature of the air movement. The land winds are strongest at about a little after sunrise and the sea-breeze at 2 P.M. or at nearly the same instant as the maximum of temperature. The morning minimum is accelerated as the season advances, whilst the evening minimum is retarded. The effect of the increasing temperature from January to April is hence to lengthen the period of the sea-breezes and diminish that of the land-breezes (by a total amount of 5 hours) between January and April. The diurnal variation during the remainder of the year, May to October, consists of a single oscillation, the maximum velocity occurring from about 2 p. m. and the minimum shortly after midnight. The ratio of the maximum to the minimum velocity in the diurnal variation is fairly constant throughout the period.


The following is a picturesque description of the setting in of the monsoon in Travancore by Mr. J. A. Broun F. E. S., a late Director of the Trivandrum Observatory: —


“There is no place in India where the magnificent phenomena which precedes the bursting of the monsoon can be seen and studied with more ease than on the Agustia Peak. For a month or more before the final crash of the tempest, the whole operations of the great atmospheric laboratory are developed at our feet, while the summit of the mountain itself is rarely visited by the storms which rage over its western flanks. In the morning, chains of finely formed cumuli seem to rest over the sea horizons of Malabar and Coromandel. Frequently it is evident that what appears a serried file of cloud masses is only cumuli irregularly distributed over the country; their shadows, projected near noon, spot and chequer the plains and the undulating country below from sea to mountain. Early in the morning the vapours begin to rise near the western precipices; the cloud accumulates and seeks to pass by the lowest cols into the eastern valleys; it seems opposed by a repulsive influence, for no breath of air is felt; it ascends at last, after noon, in mighty masses crowned with cirrous clouds which spread eastwards like an immense parasol over our heads.


“Then the lightning begins to play, darting in varied and ramiform circuits from cloud to cloud; the thunder rolls, at first in sharp separate crashes, and at last continuously; the rain is heard drenching the forests below. After an hour, or several hours, according to the distance from the monsoon, the clouds quit the mountains, move more westwards, and then disappear; the sun shines out again over the western sea, assuming before setting the most fantastic forms; the stars sparkle in all their beauty, and the morning again appears with its chains of clouds on the horizon. As the time for the monsoon draws near, the cloud masses seek with more and more energy to pass the mountains eastwards; sometimes two such masses present themselves, — one creeping up an eastern valley, the other entering the col from the west. Nothing can be more interesting than to watch this combat of the vapours. Day by day the western clouds enter a little farther; at last they come driven on by a giant force, — rise to the tops of the mountains, and pour over their walls into the eastern hollows, like the steam from a great caldron; they plunge first downwards Niagaras of cloud and then as they curl upwards, they disappear, absorbed in the hotter eastern air. The storm, with deluges of rain, sweeps over the mountain, and the monsoon reigns over the low lands of Malabar.”*


NOTEs: * Trevandrum Magnetical Observations, Vol. 1


Storms. The storms that usually frequent the Indian Peninsula and the adjacent seas belong to the class called “Cyclones”. In a cyclone, the wind blows in spiral curves, more or less circular in form, round a centre of low pressure, increasing in force as it approaches the centre. The whole cyclone thus constituted, besides turning round a focus, has a straight or curved motion forwards, so that, like a great whirlwind, it is both turning round, and, as it were, rolling forwards at the same time.


It is an important feature of -the climatology of Travancore that it is mostly free from the track of storms of any kind. The chief causes that contribute towards this end are its geographical position and its natural features providing it with a mighty wall of mountains on its eastern border. It is well known that the immediate vicinity of the Equator is never frequented by cyclones. According to Mr. Elliot, Lat. 8° N. appears to be the boundary line to the south of which cyclonic storms are seldom or never generated. Further, cyclones do not form so generally on land as over sea area, and Travancore is effectively protected by its mountains from the few storms that, having originated in the Bay of Bengal, enter the Arabian sea across the Peninsula.


Mr. Elliot says: — “It is probable that it is only storms which extend to an exceptional height into the upper atmosphere which sui-mount this obstacle It may be taken as generally true that any storm crossing the Peninsula into the Arabian sea, no matter what its original or subsequent intensity, will have relatively little influence on the weather over the narrow strip of land intervening between the Ghauts and the Arabian sea or over the sea adjacent to the west coast of the Peninsula.”


This is because of the circumstance that on the storm encountering the Ghauts, the whole of the lower circulation is broken up, and the descent subsequently effected is carried out slowly, not by the sudden and abrupt descent of the disturbance, but by a gradual downward extension of the cyclonic motion into the unaffected surface strata of the air. Hence it is not till the cyclone has advanced to some distance from the coast-line that the full effects of the phenomenon are experienced, and that the storm becomes fully recognisable. Thus the occurrences of storms in Travancore are few and far between. Besides, it is only a heavy torrential rain accompanied by a barometric depression that is often felt on land as the effect of the passage of many a cyclone through the Arabian sea near the Travancore coast.


Two instances can, however, be traced of severe storms that have been felt in Travancore, one in April 1779 and the other in December 1845. About the middle of April 1779 a hurricane was felt off Anjengo in which the East India Company’s ship Cruiser was lost. At the close of November 1845, a cyclonic storm was formed over the Bay of Bengal, which passed across the Indian Peninsula and travelled north-westward into the Arabian sea. That this storm raged throughout Travancore can be inferred from the following excerpts: —


Trivandrum


The wind blew very strongly at 1 a. m. of the 3rd December, and a violent gale lasted from 2:30 a. m. to 3 a. m. The wind then abated for half an hour after which it recommenced with greater violence than ever, and continued till about day-break. Three inches of rain fell during the second. The barometer fell three-tenths of an inch between 8 a. m. on the 2nd and 2 a. m. on the 3rd, while it rose upwards of 0.3 inch during the next 7 hours. The barometric readings at Trivandrum during the passage of the storm are given below.




QUILON.— The Master Attendant wrote: — “The gale commenced at 10 PM. of the 2nd and continued till 7 a. m. 3rd.”


Alleppey. — The Master Attendant wrote: — “A gale of wind with rain commenced about midnight, 2nd, and continued till day-light, 3rd when it blew a hurricane.”


Mr. Bailey wrote to General Cullen from Kottayam — “We were visited at Kottayam, on the morning of the 3rd instant by the same gale of wind to which you refer. Many trees were blown down or rather broken off near the roots. A good many tiles were blown off the roof of our printing office. Many persons had very narrow escapes, and three individuals at some distance from us lost their lives, and it is supposed many more”


Earthquakes


Earthquake shocks of greater or less intensity have passed through some portion or other of the Travancore territory on the following dates —


1. February 1823


2. 19th September 1841


8. 23rd November 1845


4. 11th August 1856


6. 22nd August 1856


6. 1st September 1856


7. 10th November 1859


8. 8th February 1900


9. 28th May 1903


A short account of the occurrence of each of these earthquakes is given below. —


February 1823. This shock was felt at Palamcottah slightly, and by the Rev. C. Mault at Nagercoil, and, an account of the shock as felt at the latter place was published in the Madras Government Gazette, by Captain Douglas, then stationed at Nagercoil. Nothing further is known of this earthquake.


19th September 1841. The shock as felt at Trivandrum seems to have been pretty severe, as the people at church at the time of the shock, immediately left it, fearing that the building might come down on them. The vessel supplying water to the Wet Bulb thermometer in the Observatory was shaken off its stand and broken, and several mud houses were thrown down in the Fort and elsewhere. It began in the east and passed off to the west. This shock was felt throughout South Travancore and at Palamcottah. The time noted at the Trivandrum Observatory was 11 h. 20 m. A. M.


23rd November 1845. Rev. B. Bailey (in a letter to General Cullen dated 8th December 1845 wrote —


“ On Sunday the 23rd ultimo (November) we were visited at about 2 o’clock p.m. by a slight shock of earthquake, succeeded by a rumbling noise resembling that of distant thunder... when my house was shaken to the foundation and the whole of the beams and timber gave a sudden crack as if the house rocked east and west. The shock was felt all over Kottayam”. This shock does not appear to have been perceived at Trivandrum.


11th August 1856. A shock was felt on this date at 5h. 51m. 25 s. A.M. as noted down by the Assistant on watch in the Observatory. The shock lasted 20 seconds. The magnetic instruments do not seem to have had any vibration or change of mean positions. The shock has also been felt at Parassala, Quilon, Courtallam and Pallam. It was not felt near Cape Comorin nor at Nagercoil and Agastyamala. Mr. Broun considered that the shock must have come from a direction between north and west.


This earthquake was thus described by Mr. Broun in a letter to the Madras Athenaeum in 1856 —


“The Assistant in the Trivandrum Observatory having the watch on the morning referred to (11th April 1856), was entering an observation when he heard a low rumbling sound which he thought at first was distant thunder towards the north-east; in about 3 seconds the rafters of the building began to crack, the windows to rattle and a mirror resting on the table to shake; he immediately looked at the clock and found the time 5h. 51 m. 30s, which allowing for the clock error would give the mean Trivandrum time of the commencement of the sound 5h. 51 m. 25s. He then went out to look towards the north-east and immediately thereafter the sound ceased with a louder ‘boom’; on looking again at the clock the time by it was 5h. 54 m. and he estimated the duration of noise and shock at nearly 20 seconds. He now examined the magnetical instruments, but could perceive neither vibration nor change of mean position. It is not impossible however that the magnets might have had swinging or dancing motions without being remarked by the observer as vibrations round a vertical axis only are noted. An examination by myself since, of the observations made before and after the shock, confirms the fact of the steadiness of all the magnets.


The velocity of the winds from north-west was nearly as usual at the same hour; the sky was nine-tenths clouded, the clouds moving from north-west, the temperature of the air was nearly 73°, the maximum temperature of the day being nearly 78°. The shock it seems was felt at Quilon about six o’clock’ and Mr. Liddell at Charlios Hope near the road between Quilon and Courtallam says, ‘we had a smart shock of an earthquake about 10 minutes before six on Monday morning.’


“I was on the summit of our highest mountains, the Agustier Malay (about 30 miles W. N. W. of Trivandrum) on Monday the 11th but did not perceive any shock. The testimony on the whole seems to indicate a southerly and easterly point as the direction of the origin, all agreeing that the sound was heard before the shock was perceived”.


22nd August 1856. The shock was felt at 4h. 25m.10s. P.M. The magnetic instruments were found dancing up and down with sharp jerks and a brass weight hanging in a closed box was observed by means of a telescope to dance perceptibly 15 m. after the shock. The shock passed from west-north-west to east-south-east. The Bifilar magnetometer vibration at 4 h. 30m. was 3.0 scale division, whereas at the hours before and after, it was only 0.6 scale division. This shock was also felt at Quilon about 4 h. and 16 m. and at Pallam. No shock was felt at Cochin or at Courtallam, nor to the south of Trivandrum.


1st September 1856. The time of the shock was 12 h. 44 m. 58 s, noon*. The direction of the shock as ascertained by a lead weight hung by a silk thread 17 feet long was from N. 30° W. to S. 30° E. The Bifilar magnetometer vibrated through 14.6 scale divisions at 1h.30m. This shock was felt at Cape Comorin, Nagercoil, Neyyur, and the Tinnevelly District. It does not seem to have been felt at any place north of Trivandrum.


NOTEs* In a letter published at Page 113, Vol 1 New series, of the Madras Journal of Literature and Science, Mr. Broun, the then Government Astronomer gives the time as 15 m. 0s afternoon


10th November 1859. A shock was felt at 10h.31m.47s. A.M. both the Unifilar and the Bifilar magnetometers were observed to dance up and down. The long pendulum referred to above had a slight motion from N. 30° W. to S. 30° E.


8th February 1900. A pretty severe shock was felt at 2h. 56m. A.M. On this date the magnetic instruments were not observed. The shock was felt to pass from N. to S.


28th May 1903. A slight shock was felt at 2h.46m. P.M. The magnetometers were visibly affected, and the Bifilar vibrated through 10.7 scale divisions.


Besides the above, the magnetic instruments in the Observatory have often indicated the occurrence of earthquakes elsewhere but not felt in Travancore. The most important of such indications were those of the shock that passed through the Districts of Madura and Tinnevelly on March 17th 1856 and the famous Calcutta earthquake of 12th June 1897. An examination of the magnetometer observation on the night of the 17th March 1856 at Trivandrum and Agastyamala shows that the shock may have passed the line of the Ghauts and Trivandrum before 11h.30m p.m. Mr. Broun says, “the time of the night and the little habit the natives have of observing, may partially explain the fact that the shock was not felt at Trivandrum”.