Beitrage zur Fixsternenkunde. 1. Methode, die scheinbaren Durchmesser sammtlicher Fixsterne in Bogenmass zu bestimmen, pp. 623-634). 2. Gedanken uber die Moglichkeit, die absoluten Entfernungen und absoluten Durchmesser der Fixsterne auf rein optischem Wege zu bestimmen, pp. 635-641. 3. Methode, die Geschwindigkeit, mit der die Lichtmolekel bei der Wahrnehmung der Fixsterne am Orte des Beobachters schwingen, zu bestimmen, pp. 642-647. Three bound extracts from Abhandlungen der Koniglichen Bohmischen Gesellschaft der Wissenschaften, von den Jahren 1845-1846, Volume 4 pp. 621-647. [3 PAPERS, EACH AN EXTENSION BY DOPPLER SUPPLEMENTING HIS PIVOTAL 1842 EPONYMOUS DISCOVERY]

Prague: Gottlieb Haase & Sons, 1846. 1st Edition. FIRST EDITION OF THREE PAPERS BY CHRISTIAN DOPPLER DETAILING EXTENSTIONS OF & SUPPLEMENTS TO HIS SEMINAL 1842 PAPER ON THE DOPPLER SHIFT. A handsome Sammelband binds the three works together. The papers are detailed below. Each furthers Doppler's efforts to determine the size and distance of fixed stars.

While Christian Johann Doppler contributed many papers on mathematics and electricity, "his scientific fame rests... on the discovery of what was later called ‘Doppler's principle' [shift or theory], an equation relating the observed frequency of a propagating wave to the relative motion of the observer with respect to the source of vibration" (Roguin, "Christian Doppler, the Man Behind the Effect", The British Journal of Radiology, 75 (2002), 615-619). Put another way, Doppler's equation "relates the observed frequency of a wave to the motion of the source or the observer relative to the medium in which the wave is propagated... The correct elementary formula is derived for motion of source or of observer along the line between them" (DSB). In the three papers offered here, Doppler extends his theory to the motion of both source and observer AT THE SAME TIME. Doppler's "technique has provided the science of astrophysics with one of its most important tools for measuring the size and the structure of the universe" (DSB).

The first of Doppler's three papers presents a method to determine the apparent diameter of all fixed stars in an arc.

The second, presents his thoughts about the possibility of determining the absolute distances and absolute diameters of the fixed stars in a purely optical way. In it, Doppler also suggests employing photography as a tool in astronomical research. Specifically, Doppler "calculated the resolution that could be obtained with a photographic plate, estimating that it was 40,000 times more susceptible to impressions than the human eye. He thus recommended that astronomers concentrate on magnifying the image made on a photographic plate by a stellar or planetary object through a telescope, instead of trying to increase the telescope's power, which he believed was reaching its limit" (New World Encyclopedia).

The third, presents a method to determine the speed with which the light molecules oscillate when the fixed stars are perceived at the observer's location. CONDITION & DETAILS: Prague: Gottlieb Haase & Sons. Complete. 4to. (11 x 8.75 inches). New Sammelband in period style binding. Half calf over marbled boards; gilt-lettered at the spine; purposefully aged paper label on the front board. 1 Plate. [4], 2, [pp. 623-646], 2, [4]. Includes original title page to the 3 papers. Very light spotting within. Largely bright and very clean. Very good + condition.