H. Molm. Astronomiske Observationer til Tids- og 8teds- bestemmelse. e i denne Afhandling meddelte astronomiske Observa- tioner gjordes under Expeditionens Opliold i Havn vsesentlig med det Maal for 0je at tjene til Grundlag for de Tids- og Azimuthbestemmelser, der udfordredes til de magnetiske Iagttagelser. Ved Siden deraf tilsigtedes ogsaa Bredde- og Lamgdebestemmelser, der kunde vaere af geo- grafisk Interesse, som paa Jan Mayen og Spidsbergen. Den gunstige Lejlighed, soin de gjennem Telegrafen givne Tids- signaler frembod til Verification af Lsengden af Punkter paa Kysten af det nordlige Norge, onskede jeg ogsaa at benytte efter Lejligbeden. Observationerne ere Solhojder. maalte med Sextant. Af Bestyreren for det astronomiske Observatorium i Chri- stiania, Professor C. Eearnley, fik jeg udlaant en Observa- toriet tilhorende Sextant af Troughton. med Kviksolvliori- zont og Stativ, det samme Instrument, som Hansteen be- nyttede paa sin Bejse i Sibirien i Aarene 1828—1880. I Brugen af Instrumentet niodtog jeg selv Prof. Hansteens Vejledning paa Observatoriet i 1861. Paa Sextanten af- laeses ved Nonien directe 10". Ved samtlige Observationer benyttedes den lange Kikkert med ca. 10 Ganges Forstor- ring. Glastaget over Kvikselvliorizonten provede jeg, paa Rost, ved at stille det foran Kikkerten paa en Theodolitk, der var indstillet paa en god Mire (et Kirkespir); Virk- ningen af en prismatisk Form af Glassene var saagodtsom umerkelig, og kan neppe udgjore et Par Sekunder. Saagodtsom alle de her meddelte Observationer ere gjorte med dette Instrument. Under Jan Mayen observe- redes fra Skibsborde ogsaa med et Par andre Sextanter. Af Uhre liavdes i 1876 ombord 3 Boxchronometre, af Kullberg, Frodsliam og Mewes saint et Lommeclirono- meter, foruden almindelige Lommeuhre, bvoraf et mig til- horende Duplexuhr. I 1877 og 1878 bavde vi foruden de nsevnte Uhre et Boxchronometer af Reid og i 1878 liavde l)en norske Nordlinvsexpedition. II. Molm: Astronomiske Observationer. H. Mohn. Astronomical Observations for determining Time, Latitude and Longitude. The astronomical observations set forth in this Me- moir were made during our stay in certain of the harbours at which the Expedition touched, — chiefly to serve as a basis of the time and azimuth determinations required for the magnetical observations. A secondary ob- ject lay in performing, if possible, divers latitude and longitude determinations that might prove of geographical interest, as, for instance, on the islands of Jan Mayen and Spitzbergen. Moreover, of the excellent opportunity afforded by the telegraph time-signals to verify the longitude of points on the northern line of the Norway coast, I was specially desirous of taking advantage. The observations are solar altitudes, measured with the sextant. On application to Professor C. Fearnley, Di- rector of the Astronomical Observatory at Christiania, lie kindly lent me a sextant belonging to that establishment, one of Troughton’s, furnished with a mercury-horizon and stand, -— the identical instrument used by Hansteen on his travels in Siberia (1828—1830). In the use of the in- strument Hansteen had himself given me the necessary in- structions. at the Observatory, in 1861. The vernier reads 10 seconds. For all the observations, the long telescope, magnifying about 10 diameters, was exclusively used. The glass covering the mercury-horizon I tested at Rost, by placing it in front of the telescope of a theodolite directed to a good mark (a church steeple). The effect resulting from a slightly prismatic form in the glasses was well-nigh inappre- ciable, amounting as it did to hardly a couple of seconds. Almost all of the observations were made with this instrument, a very few only having been taken on board with other sextants, off the coast of Jan Mayen. Of time-keepers, we had on the first cruise, in 1876, 3 box-chronometers, made respectively by Kullberg. Frod- sbam. and Mewes. and a pocket-chronometer, exclusive of watches, one of which — that belonging to myself — was a duplex lever. In 1877 and 1878, we had in addition a l

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