Nature . always be carefully washed for somehours, in order to get rid of all trace of the hyposulphateof soda. It is an exceedingly easy matter to quickly •dry photographic plates ; but most methods, even thatof the use of alcohol, are inclined to create disturbancesin the film, such as unequal contraction, which render itunfit for accurate measurements afterwards. Herr Witt therefore waited until the following daybefore the negatixe was examined. Not only did hefind on it the record of the long-lost minor planet hewas seeking after, but another one. Althaea (119), whichhad been previously di
Nature . always be carefully washed for somehours, in order to get rid of all trace of the hyposulphateof soda. It is an exceedingly easy matter to quickly •dry photographic plates ; but most methods, even thatof the use of alcohol, are inclined to create disturbancesin the film, such as unequal contraction, which render itunfit for accurate measurements afterwards. Herr Witt therefore waited until the following daybefore the negatixe was examined. Not only did hefind on it the record of the long-lost minor planet hewas seeking after, but another one. Althaea (119), whichhad been previously discovered. With the help of alens a further trail was noticed, but on account of itsunusual length, which was an indication of a quickmoving body, he thought at first it must be a verify this conclusion, the following evening he turnedthe 12-inch refractor towards the same region, and foundin that position a stellar- not cometary-like body oimagnitude 10 to 11. Without any further delay the dis-. :^ paili ul [11. .V ui ^k) At the present day numbers of workers are exposingplates on clear nights to delect both new and old mem-bers of this family, and it was during such a search thatHerr Witt, of the Urania Observatory in Berlin, madetlie important discovery of this new planet. Since the year 18S9 a certain minor planet namedEunike (183) has never been observed, and it was withtlie intention of photographing this object that HerrWitt turned his telescope, on the night of .-\ugust 13,towards the region of ,3 Aquarii, previous calculationhaving told him that the planet should be in or near thatregion, .\fter a two hours exposure the plate was de-veloped and washed, and left to dry until the next day,when it was carefully examined. It may be asked, whythe plate, after development, was not immediately«xaniined? .y one wHio is familiar with such work willknow that not only is the film very soft, and thereforeeasily liable icj be damaged, but that the trails
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
