Award of the Boyle Medal to Sir Howard Grtd)b. 289 



existence — the Washington refractor. In this instrument, not onl were the 

 optical parts of the highest excellence, but the mounting marked a new 

 departure, and placed in the hands of the astronomer facilities he did not 

 previously possess. The anti-friction arrangements of the bearings were of a 

 most ingenious type, especially in their application to the declination axis, in 

 which tliey were successfully carried out in this instrument for the first time. 



The first instruments in whieli declination was read from the eye-end of 

 the telescope seem to be the 15-iuch equatorial by Grubb, and the 6-inch 

 instrument by Cooke erected for Lord Crawford at Dun Edit, Aberdeen, 

 about 1873. The plan is now universally adopted. It was, however, reserved 

 for Sir Howard Grubb to accomplish the feat of enabling the observer to 

 read the right ascension circle from the eye-end also, and this he succeeded 

 in doing for the first time in the great Vienna telescope. 



Another interesting feature is the electrical control of the clockwork 

 for driving the telescope in right ascension. This ingenious device ensured 

 uniformity of motion under normal conditions, and also afforded a means ol 

 correcting any error which might accidentally arise. The slow motion in 

 right ascension consists of a set of differential wheels, which increase or 

 diminish the rate at which the telescope is driven, without interfering with 

 the rate of the clock or exciting any oscillatory motion in the telescope. 

 It is needless to dwell upon the influence that accuracy of control has had 

 upon stellar photography ; without it the wonderful developments of 

 recent years would not have been possible. Several of the telescopes 

 employed in the formation of the great astrographic chart of the heavens 

 (notably those at Q-reenwich, Oxford, and the Cape) were constructed by 

 Sir Howard Grubb and fitted with his clock control. 



The 26-inch refractor which Sir Howard Grubb constructed for the 

 Royal Observatory, Greenwich, exhibits these refinements in a more 

 elaborate form. 



It is not necessary to mention in detail the many famous instruments 

 Sir Howard Grubb has constructed. Suffice it to say that they are to be 

 found in observatories in Germany, Austria, Russia, Belgium, Italy, Spain, 

 Tui'key, America, the British Colonies, India, China, as well as in many 

 places in the United Kingdom. 



Sir Howard Grubb's attention has been by no means confined to 

 telescopes and their mountings. Nearly forty years ago he was Chairman 

 of the Committee of Science when it was decided to institute a system 

 of electrical control of the clocks of Dublin. A Report, published as an 

 Appendix to the Minutes of the Council (Proceedings, vol. ex), shows that 

 at that time no public clock in Dublin showed the true time, the error in 



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