Ponta Delgada Research Articles

The lunar atmospheric tide in the Azores, 1894‐1932

AbstractThe lunar atmospheric tide is determined at two stations in the Azores, namely, Ponta Delgada (38° N., 26° W.) and Santa Cruz (39° N., 31° W.), from 39 to 26 years' bi‐hourly data (all days) for the barometric pressure. The mean results are respectively 22 sin (2t + 55 °) and 18 sin (2t + 58°) in microbars, so that high tide occurs 72 and 65 (solar) minutes after lunar transit. As at most other stations, the tide is distinctly later near the December solstice than at other times. The probable errors of these mean results are 1.6 and 2.2 microbars.The harmonic coefficients for the first four components of the solar diurnal variation are also given.

Observations in the Azores, May 28–30, 1919

Special magnetic observations were made in this Island of S. Miguel (Azores) during the solar eclipse of May 29, 1919, in accordance with the program of the Department of Terrestrial Magnetism.In the garden of my house I have, since 1899, a pier on which I make absolute measurements of the magnetic elements, to compare with those observed at the Magnetic Observatory of S. Miguel, established near Ponta Delgada, under my general direction. In this garden I have also a Mascart declinometer, with which on May 29, during the interval of 9h 58m to 16h 32m, Greenwich civil mean time, were made at every minute observations of the declination. Since the results of these eye‐readings of the declination agree perfectly with those of the eye‐readings, made with a similar instrument at the Magnetic Observatory, only the results of the latter observations are given here. [Table 1 contains the five‐minute means.]

The Spread of Injurious Insects

IN 1898 Dr. L. O. Howard forwarded to me a scale insect discovered by Prof. Chaves at Ponta Delgada, Azores, attacking the foliage of the orange tree. The insect proved to be new, and was described as Lecanium perlatum. Since that time it has never been reported from any other place; but now I have received some large, flat, dark brown scales on orange leaves from Villa Encarnacion, Paraguay, collected by Mr. Schrottky, and they are this very same L. perlatum.1 This is only one new case to be added to the many already known of scale insects being transported from one side of the world to the other, evidently by human means. It is to be regretted that the British Government, with its numerous tropical colonies and excellent botanical gardens, has not done something to make known the scale insects within its domains. It is true that Mr. E. E. Green, the Government entomologist of Ceylon, is bringing out a magnificent work on the scale insects of that island; but he finds insufficient support, and it is divulging no secret to say that the publication of this useful book will involve him in very serious financial loss. There is no properly classified national collection of scale insects (the only good collection in England is that of Mr. Newstead at Liverpool), and we are still totally ignorant of the coccid fauna of many colonies. The reasons for regretting this condition of affairs are mainly two:—(1) because in ignorance pests of this group are continually being carried to new regions, where they are liable to become destructive; and (2) because man is so mixing up the distribution of these insects that every year makes it more difficult to ascertain their natural habitats. Having regard for the experiences of the past, it is surely safe to say that the annual expenditure of a few hundred pounds in the investigation of these pests would be far more than repaid in economic as well as scientific gains.

Record of the great magnetic storm of October 31, 1903, at Ponta Delgada, Azores

The “Gauss” of the German Antartic expedition, arrived at Ponta Delgada, Azores, on October 28, 1903, on its return from the Antartic regions. On October 30th, Dr. Bidlingmaier, in charge of the magnetic work of this expedition, began to make magnetic observations at various points on St. Michael's Island. I, accordingly, took eye readings of the magnetic declination to supply the necessary reductions for his work. We both began at 7 A. M., local mean time.

IV. Note on the determination of magnetic inclination in the Azores

With the exception of a series of determinations made by the officers of the “Challenger” at Ponta Delgada, St. Michael, in 1873, no magnetic observations have, so far as I can learn, been made in the Azores since the time, of Captain Vidal’s hydrographic survey in 1843-4.

Notice of the Occurrence of an Earthquake Shock in the Azores

The following are the particulars of an earthquake felt in the Azores on the night of April 16, 1852; distinguishing the islands from which information has been obtained. St. Mary's; 0°32′ East of the point of observation at St. Michael's. Communicated by Major Guerra, a highly intelligent officer of the Portuguese army, resident at St. Mary's, to his correspondent here. Point of Observation. —The chief town of Villa do Porto, situated on the south-west coast, about 200 feet above the level of the sea, and separated from it by a slightly ascending plain, nearly three miles wide, and W.S.W. (true) of the base of the central ridge, of which the principal peak, Pico Alto*, is 1880 feet in height above the sea. Time and Phenomena. —At a little more than five minutes after ten (10h 8m at St. Michael's?), a slight subterraneous rumbling was followed by a sufficiently perceptible oscillation from south to north, ending in a strong shock, and lasting not less than three seconds. Effects. —No damage appears to have been done to houses and public buildings. St. Michael's; Point of Observation 25° 41′ West of Greenwich. Point of Observation. —The chief town of Ponta Delgada, close to the sea, at an elevation of 70 feet, on an ascent which in about three miles reaches to the top of the central ridge of the island, which in this part rises into peaks of between 1000 and 1600 feet above the sea. Time and Phenomena. —A distinct but not loud rumbling was heard by some persons for about three seconds, and after a perceptible interval, a slight oscillation was

VII. A narrative of the eruption of a volcano in the sea off the Island of St. Michael

Approaching the island of St. Michael’s, on Sunday the 12th of June, 1811, in His Majesty’s Sloop Sabrina, under my command, we occasionally observed, rising in the horizon, two or three columns of smoke, such as would have been occasioned by an action between two ships, to which cause we universally attributed its origin. This opinion was, however, in a very short time changed, from the smoke increasing and ascending in much larger bodies than could possibly have been produced by such an event, and having heard an account, prior to our sailing from Lisbon, that in the preceding January or February a volcano had burst out within the sea near St. Michael’s, we immediately concluded that the smoke we saw proceeded from that cause, and on our anchoring the next morning in the road of Ponta del Gada, we found this conjecture correct as to the cause, but not to the time; the eruption of January having totally subsided, and the present one having only burst forth two days prior to our approach, and about three miles distant from the one before alluded to. Desirous of examining as minutely as possible a contention so extraordinary between two such powerful elements, I set off from the city of Ponta del Gada on the morning of the 14th, in company with Mr. Read, the Consul General of the Azores, and two other gentlemen. After riding about twenty miles across the NW. end of the island of St. Michael's, we came to the edge of a cliff from whence the volcano burst suddenly upon our view in the most terrific and awful grandeur. It was only a short mile from the base of the cliff, which was nearly perpendicular, and formed the margin of the sea; this cliff being as nearly as I could judge from three to four hundred feet high. To give you an adequate idea of the scene by description is far beyond my powers; but for your satisfaction I shall attempt it.