Beyond the introduction of the spider line it is unnecessary to mention the various steps by which the Gascoigne micrometer assumed the modern forms now in use, or to describe in detail the suggestions of Hooke, 4 Wren, Smeaton, Cassini, Bradley, Maskelyne, Herschel, Arago, Pearson, Bessel, Struve, Dawes, &c., or the successive productions of the great artists Ramsden, Troughton, Fraunhofer, Ertel, Simms, Cooke, Grubb, Clarke and Repsold.
Equatorial made for Struve at Dorpat by Fraunhofer; it was completed in 1825.
Struve published an account of the application of clockwork as an aid in Repsold's method; and, later, Dr Cohn published a more elaborate paper on the same subject in the Astron.
Struve in 1848, and those relating to occultations of the Pleiades were discussed by Carl Linsser in 1864.
But while Struve, and to a less degree Plekhanov, were induced by this admission to seek an affiance with Liberal intellectuals in their struggle against Tsarism, Lenin (as he had taken to calling himself), together with Martov, Axelrod and other fiery spirits, forsook the Liberal platform and strove for a violent outbreak of a downright class war.
The disillusionment as regards material means for improving the life of mankind had given rise in many minds to a quest for religion, and this mystic current had attracted men like Struve, Bulgakov, Berdiayev and others.
Struve (St Peters.
In conjunction with Struve he drew up the Radical programme carried at the great Liberal meeting held at Offenburg on the 12th of September 1847 (entitled "Thirteen Claims put forward by the People of Baden").
On the 12th of April Hecker and Struve sent a proclamation to the inhabitants of the Seekreis and of the Black Forest "to summon the people who can bear arms to Donaueschingen at mid-day on the 14th, with arms, ammunition and provisions for six days."
4) that Bessel had indicated, by notes in his handbooks, the following points which should be kept in mind in the construction of future heliometers: (I) The segments should move in cylindrical slides; b (2) the screw should be protected from dust; 6 (3) the zero of the position circle should not be so liable to change; 7 (4) the distance of the optical centres of the segments should not change in different position angles or otherwise; 8 (5) the points of the micrometer screws should rest on ivory plates; 9 (6) there should be an apparatus for changing the screen.'° Wilhelm Struve, in describing the Pulkowa heliometer,' 1 made The distances of the optical centres of the segments from the eye-piece are in this method as I; secant of the angle under measurement.
Struve also points out that by attaching a fine scale to the focusing slide of the eye-piece, and knowing the coefficient of expansion of the metal tube, the means would be provided for determining the absolute change of the focal length of the object-glass at any time by the simple process of focusing on a double star.
It is probable that the Bonn heliometer was in course of construction before these suggestions of Struve were published or discussed, since its construction resembles that of the Konigsberg and Pulkowa instruments.
This instrument suggested to Struve the abovementioned idea of employing a similar motion for the heliometer.
Focal length) from the Repsolds, and the design for their construction was superintended by Struve, Auwers FIG.
Struve (Description de l'Observatoire ' Central de Pulkowa, pp. 196, 197) adds a few remarks to Steinheil's description, in which he states that the images have not all desirable precision - a fault perhaps inevitable in all micrometers with divided lenses, and which is probably in this case aggravated by the fact that the rays falling upon the divided lens have considerable convergence.
If Struve had employed a properly proportioned double circular diaphragm, fixed symmetrically with the axis of the telescope in front of the divided lens and turning with the micrometer, it is probable that his report on the instrument would have been still more favourable.
This particular instrument has historical interest, having led Struve to some of those criticisms of the Pulkowa heliometer which ultimately bore such valuable fruit (see ante).
Von Struve (1820-39), and partly to Fraunhofer's.
Lommel, Lord Rayleigh, Georg Wilhelm Struve); the theory of elasticity (A.
FRIEDRICH GEORG WILHELM STRUVE (1793-1864), German astronomer, the son of Jacob Struve (1755-1841), was born at Altona on the 15th of April 1793.
This work was afterwards extended by Struve and General Tenner into a measurement of a meridional arc from the north coast of Norway to Ismail on the Danube (Arc du meridien de 25° 20' entre le Danube et la Mer Glaciale, 2 vols.
(See Geodesy; Earth, Figure Of.) His Son Otto Wilhelm Struve (b.
Another Son, Heinrich Wilhelm Struve (b.
Karl Hermann Struve (b.
Gustav Wilhelm Ludwig Struve (b.
The generally accepted value is 20.445", due to Struve; the last two figures are uncertain, and all that can be definitely affirmed is that the value lies between 20ï¿½43" and 20.48".
Fraunhofer's chef-d'oeuvre, the great Dorpat refractor, made for Otto Struve about 1820, had a mounting of this type, and was the first equatorial of any importance to be provided with clockwork.
13, is described in detail by Struve (Beschreibung des auf der Sternwarte zu Dorpat befindlichen grossen Refractors von RIH? ?
In the hands of Struve results were obtained by it which in combined quality and quantity had never before been reached.
When, twelve years afterwards, Struve ordered the is-in.
We have the authority of Otto Struve for stating that in practice they are all that can be desired.
Struve at Dorpat examined 120,000 stars, and found 3112 double stars whose distance apart did not exceed 32".
Struve A = 18 h 20 m D = +23° 5 S.
Struve developed the view that the stars are contained in a comparatively thin stratum bounded by two parallel planes.