Sidereus Nuncius
The first telescopes appeared in the Netherlands in 1608 when Middelburg spectacle-maker Hans Lippershey tried to obtain a patent on one. By 1609 Galileo had heard about it and built his own improved version. He probably was not the first person to aim the new invention at the night sky but his was the first systematic (and published) study of celestial bodies using one. One of Galileo's first telescopes had 8x to 10x linear magnification and was made out of lenses that he had ground himself. This was increased to 20x linear magnification in the improved telescope he used to make the observations in "Sidereus Nuncius".
Mikhail Lomonosov
In 1762, Lomonosov presented an improved design of a reflecting telescope to the Russian Academy of Sciences forum. His telescope had its primary mirror adjusted at an angle of four degrees to the telescope's axis. This made the image focus at the side of the telescope tube, where the observer could view the image with an eyepiece without blocking the image. However, this invention was not published until 1827, so this type of telescope has become associated with a similar design by William Herschel, the Herschelian telescope.