Sentence:  After making a sketch of the <WSD>Neptunian</WSD> regions for the dates from 1790 to 1800, I soon came to the conclusion that the nights of the 8th and 10th of May, 1795, were the only ones that afforded a reasonable prospect of furnishing an observation of Neptune, and accordingly computed for the evening of the 10th of May, the limits of the <WSD>Neptunian</WSD> region, or in other words the "locus" of Neptune as a fixed star, [...] 
Meaning of the word marked with <WSD> tags:  Of or pertaining to the planet Neptune.