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COMMUNICATION FROM A. FENDLER.
Colonia Tovar, VENEZUELA, SOUTH AMERICA,
August 5, 1856. DEAR SIR : I sailed from Philadelphia on the 5th of May, and arrived at Laguayra three weeks after. Colonia Tovar I reached on the 7th of June, and commenced my meteorological observations on the 10th. The barometer and the dry and wet bulb thermometers, which by your kindness I received from Mr. Green, I have brought home safe and in good order.
Accompanying this I send you two registers of meteorological observations of the month of June and July, 1856; and here I have to make the following remarks :
1. As I am very much interested in the results of the observations, I need not say that I pay the most particular care and attention to the condition of the instruments, as well as to the nicety in taking observations and in noting them down.
2. The column under the head of “Barometer height recluced to freezing point,” I could not fill up for want of the necessary tables.
3. By comparing my old thermometer, which is one of the more common kinds, marked “T. Barry, London,” with the Smithsonian dry bulb thermometer, I found that the former is from one and a half to five degrees too high; so that I was obliged to use the dry bulb of the psychrometer also as thermometer in the open air. The wet bulb was therefore exposed to the open air also. According to the first principles of evaporation it is, however, evident that the more rapid the motion of air is which touches the wet bulb the more energetic will be the evaporation of the water contained in the wet linen, and the lower will the mercury sink. This I found to be confirmed by every breeze, and even the lightest breath of wind that happened to strike the wet bulb at the time I took observations. I therefore regard all observations with the psychrometer, that are not taken in a calm atmosphere, or in an atmosphere the velocity of which at the time of observation is known, as of little value.
As I had no other standard thermometer besides the dry and wet bulb, I can give the psychrometrical observations only, with the remark that they are worth just as much as all other such observations made in the open air without regard to the currents of the atmosphere. In future I shall try to shelter the wet bulb against the influence of wind at the time of observation.
4. As I have no rain gage I can only put down the time of beginning and ending of rain.
5. With regard to clouds I may say, that the higher clouds are mostly hidden from view by the masses of lower clouds, so that the course of the former can very seldom be ascertained in the rainy season, and, when seen, there are several strata, one above the other. Instead of the higher clouds, I have carefully noticed and put down
the course of the lower clouds, under the head of "winds." The motion of these lower clouds may justly be said to indicate the real course of the wind; for in such a mountainous country as this the atmosphere at the bottom of the kettle-shaped valley of the colony, is set in motion by a great number of local causes, and this motion is changed and modified by the many ravines and watercourses, and by every slope of the irregularly shaped mountains. The colony is surrounded by mountain ridges, crowned by several peaks. These barriers open only in one direction, towards the east, where they form an outlet for the river Tuy, which has its sources in the neighboring fields and adjacent forests. In such a region as this it is next to impossible to pote, even in one narrow district, all the different little breaths and jerks of wind, which frequently change every moment.
As to the motion of the lower clouds, they frequently showed a velocity which I estimated at about 7 miles per hour ; and as there is no number corresponding to this velocity in the tables, I introduced the number “21,” which means 7 miles per hour.
Fog is a considerable item in this region in the rainy season, and I have accordingly noted it down under the head of “kinds of clouds."
Thunder and lightning are very rare here, and when they occur they make so little show that, with regard to force, they may be compared to those of the United States as the zephyr to a strong gale. In the register I have noted them down in the margin.
Tornadoes I have never seen in the colony, not even a gale of wind, within the two and a half years that I have been living here. Hail storms are unknown in this part of the country.
Of the 48 observations recorded in July, at 7 a. m. and 2 p. m., on the course of the lower clouds, 10 are E., 15 E.SE., and 15 SE., which shows the prevailing winds to be between E. and SE. Their mean velocity is a fraction over four miles
hour. Of rain, fog, mist, and clouds, we had more than a sufficiency, the mean cloudiness being 6.4.
The weather has been so unfavorable since my return from the States that I have not yet measured any of the neighboring heights and passes by barometer.
The thermometer in the open air shows a mean temperature of 58.3 for the month of July, a rather low temperature for the height of 6,500 feet in latitude 10° 26'. The minimum of the month was 54°, the maximum 690
I also inclose the half-hourly and hourly barometrical observations for seven days, made in order to ascertain the hour of maximum and minimum of the daily periodical variations. And here I found that these variations within the tropics, at least at the colony, are not so regular as we sometimes find stated in books. As, for instance, the following: “Such is the regularity with which these motions are effected within the equatorial zones that they might there serve to give the true time of the day.”—(Nicollet, Essay on Meteor. Observ., page 7.) For we find maximums at 91 a. m., 10, 11, 12 m., and minimums at 4 p. m., 41, 5, 51, 6, 61, 7, and all this within the short period of seven days. This irregularity is the more remarkable, as the colony is a place where none of the extremes of heat and cold, or of
gales, hurricanes, and thunder storms are felt, that could disturb the equilibrium of the atmosphere.
Besides the two registers and the hourly observations, I have copied for you and inclosed the thermometrical observations for 12 months in 1854 and 1855. These have been taken with my old thermometer, which proves to be from 11 to 5 degrees too high, as compared with the Sunithsonian thermometer. Although this would make the mean temperature of the year about 3 degrees too high, we are still enabled to make some comparisons between the different months, which show that from August the mean monthly temperature is gradually sinking till January, which is the coldest month. After January it rises again till May, and then sinks till July. This seems to indicate that the rising and falling of the mean temperature keeps equal pace with the declination of the sun. If we now compare the means of the different hours of the day of each month, we find that the highest temperature of the day is not at 2 or 3 p. m., as in the United States, but at 12 o'clock at noon, and that the temperature at 3 p. m. is but a fraction greater than that at 9 a. m. In five months of the year it is nearly or quite the same with that at 9 a. m., viz: from November till March, inclusive; during the other part of the year, from May till September, inclusive, the mean temperature is higher at 3 p. m. than at 9 a, m., with the exception of October and April, where the temperature at 3 is even lower than that at 9; and these are the two months which follow immediately after the equinoxes. Another curious fact is the sudden rise of mean temperature from July to August. In Santa Fé de Bogota, in 4° 35' north latitude, July is said to be even the coldest month of the year.
Some other facts could, no doubt, be drawn from this register by comparison, if its observations were founded upon a standard thermometer.
On the last page of this register of Colonia Tovar you will find some observations, taken with the same thermometer, of “Barry,'' during my stay at Chagres, on the Isthmus of Panama.
During my absence from the colony last winter some persons here, who can be relied upon, have seen white frost one morning. This is of extremely rare occurrence, but anyhow very remarkable for the latitude of 10° 26', even at the height of 6,500 feet.
The characteristics of this region are its clouded sky, its equable temperature, and its great amount of moisture. It is the “happy region of the ferns," where these interesting plants find their most suitable climate and grow in the greatest profusion. Here it is where the stately tree-fern sometimes is seen to reach a height of 40 feet.
The produce most profitable to raise in the colony are potatoes, rye, and oats. The apple tree grows side by side with the banana. The strawberry is found in the greatest abundance, spontaneously growing about the fields. Indian corn does not come to maturity here, while I have seen it raised and matured in Santa Fé, New Mexico, which is at least 700 feet higher than the colony, and besides this is near 36° north latitude. But in New Mexico they have a cloudless sky nearly the whole year round and an extremely dry atmosphere, while the colonists of Tovar are not much molested from the beginning of May to the beginning of January by the rays of the sun.
The valley in which Colonia Tovar is situated was, so late as De cember, 1841, a perfect wilderness, covered with primitive forest. Not even the existence of this valley was known fifteen years ago, neither to the government nor to its ɔwner. although it is only thirtyfive miles west of Caracas, the capital of Venezuela, and in a straight line cannot be more than twelve miles from the sea. And when an attempt was made to explore this region not even a guide could be found for the small exploring party of fifteen men, headed by Colonel Codazzi, a skillful officer and compiler of the new map of Venezuela. When this party at last succeeded in crossing this region and reaching the sea-shore, they thought they had achieved a most extraordinary thing, (to cross a distance of twelve miles in eix days;) and after they had returned to their homes none of them had a desire to do the feat over again. This was a party of natives. And when, at a later period, after the establishment of the colony, another skillful engineer found, with a party of colonists, his way to the opposite port of the sea-shore, the party did not venture to go back the same route, but rather chose the way by sea to Laguayra, from there to Caracas and back to the colony, a very circuitous route certainly. Such is the nature of this mountain region, with its precipices, waterfalls, deep ravines, and its dense, almost impenetrable primeval forests.
In collectiog botanical specimens, I have penetrated, without a companion, the wilderness around in different directions, also that on the other side of the principal mountain range towards the sea, and can testify to the difficulties and hardships which are met with in exploring such a country. On excursions of this kind the most needful thing besides a compass is a short sabre, called "machetta," which I have to use continually in cutting through the lianos, the erect and climbing canes, the under shrub, which is all matted and intermingled in a thousand different ways into a dense mass of vegetation.
In these woods, where the rays of the sun never touch the ground, there it is where moisture and a cool temperature reign forever. The trunk of every tree and its branches are covered with Ferns, Lycopodiaceæ, Mosses, Hepaticæ, Lichens, Orchids, Bromeliads, Araceæ and besides Piperace with many exogenous plants too numerous to mention.
The soil in these forests is one entire mass of sleuder rootlets most completely intermingled and interwoven, more than a foot in thickness, the interstices filled with a brown but imperfectly decomposed vegetable mould, which is kept in its place by the network of the rootlets. This stratum is covered with mosses and remnants of leaves, so that on the mountain ridges not only the ground, but also the trunks and branches of the trees, act like a thick layer of sponges in retaining the water that either pours down in form of rain or settles more slowly in the form of mist and clouds. This water is allowed to trickle and sink down but very gradually, and is, therefore, a never-failing source from which are constantly fed the many little rivulets that hurry down the steep declivities into their common receptacle, the narrow chasm of the river Tuy, which, in one continued row of cascades, rushes thundering down SE. and S. until after a run of twenty miles, turning suddenly to the east, it finds a more level country.
In the depth of such a mass of vegetation, when man is by himself, a feeling of loneliness takes the ascendency over every other emotion; no animal is seen, and but seldom the voice of a bird heard. While on the sea-side of the mountains I was only made twice aware of the vicinity of a bird in two days. In the neighborhood of farms and habitations of men a greater variety of birds are seen and heard, and sometimes the grunting or howling of monkeys and the deafening cry of parrots.
The dry season commences here generally soon after New Year's day and lasts till the end of April. The remainder of the year is taken up by the rainy season. This is generally so, for there are many exceptions, and our notions about the great regularity and sharply defined seasons of the tropics, which we have received from books, are sometimes materially upset and corrected by experience. When I first came to the colony, in March, 1854, we had a dry season in its usual way. The rainy season then commenced on the 23d of April, but it did not end with the latter part of December, as is usually the case; it lasted till the end of January, and commenced again with the first of March, and then kept uniformly on till the end of December, 1855. The dry season was, therefore, only of one month's duration instead of four. The last dry season has been, on the contrary, unusually long, and lasted till the latter part of May.
I have often thought that the climate of North America may stand in some kind of relation to the climate of this country.
It was on the 24th of December, 1853, when I left New York, to sail for Laguayra.
We were hardly out of sight of land when a furious NW. gale, a real hurricane, (which is still in fresh remembrance with some of the captains I have lately seen,) during a period of three days threatened our destruction. After my arrival in Venezuela I was told that about Christmas, 1853, one of the most fearful gales from the north was felt at Laguayra.* Another question is, whether the late remarkably dry and cold winter of the United States and the unusually long dry season of Venezuela, as also the remarkable appearance of white frost in the colony, are not connected in some way or other.
As to the trade winds, I found on my trip from Philadelphia to Laguayra that within the tropics we had no E.NE. wind, which is thought to be the regular trade winds of those regions. After crossing latitude 231°, in longitude 68.1°, we were becalmed for one day, and soon after got a fresh breeze from the south, which we kept all the way to longitude 63o. By tacking we got to latitude 22° , longitude 631°. From thence we had the wind all the time from S.SE , which we kept to latitude 111° the day before we reached Laguayra. Capt. Wilkins, who has been in this southern trade for eighteen years, assured me that within the last eight years he never could depend much upon the trade winds. He finds that between latitude 230 and 18° the south wind frequently keeps on blowing very brisk for eight days in succession.
On the way from the colony to Caracas, along the high ridge of the principal mountain chain, which stretches E. and W., parallel
See page 188.