In recent years no noteworthy refractors have been mounted on Great this plan; but type A has been chosen by Grubb for the Me!- great Melbourne reflector, of 48-in.
Type C. - Many more telescopes have been made of type C than of any other, and this form of mounting is still most generally employed for the mounting of modern refractors.
13, is described in detail by Struve (Beschreibung des auf der Sternwarte zu Dorpat befindlichen grossen Refractors von RIH? ?
Both the Dorpat and the Pulkovo refractors are defective in rigidity, especially in right ascension.
Newton failed to perceive the existence of media of different dispersive powers required by achromatism; consequently he constructed large reflectors instead of refractors.