31 1 Rtpovt of the Kew Committee. 



familiar with the system of rating chronometers carried on there f< 

 many years past. 



The Greenwich trial lasts for twenty-nine weeks, the movemen 

 being tried during alternate periods of seven and fonr weeks at 

 ordinary temperature of the air, and in a hot room at temperatures 

 from about 75 to 100 Fahr. This gives a total of twenty-one week 

 at atmospheric temperatures and eight weeks in the oven. 



The difference, in seconds, between the greatest and least wee 

 rates of a chronometer during the trial being denoted by a, and 

 greatest difference, in seconds, between the rates of two euccessiv 

 weeks by 6, the smallness of the quantity a + 26 has been adopted 

 Greenwich as the measure of the excellence of a chronometer. 



At the request of the Italian Naval Attache the test at Kew w 

 to be directed to ascertain in which of the chronometers sent for tri 

 the value of a -I- 26 did not exceed 38. 



It was decided to utilise for the trial the Pendulum Chamber 

 the basement and the North room in the new wing. The former 

 constructed of wood, double walled, with a 6-inch air space all roan 

 and having been originally designed with a view to reducing tempe: 

 ture variations to a minimum, it was admirably suited for conver- 

 sion into a hot chamber. 



A gas furnace, made of copper to avoid the risk of disturbing tht 

 magnetographs, was specially built by Messrs. Fletcher, Russell, am 

 Co., of Warrington. It has given entire satisfaction, being perfectlj 

 under control, so that any desired temperature up to 100 Fahr. can 

 be reached and regularly maintained. By means of two copper flue* 

 the products of combustion are taken into the outer air, and the 

 atmosphere of the hot chamber is at all times pure and free from 

 fumes, while the presence of several open vessels of water prevent! 

 undue desiccation. 



The North room referred to above is used for the ordinary tern 

 perature tests, and in it temperatures as low as 37 Fahr. have 

 observed. In addition to the ordinary maximum and minim 

 thermometers a " Richard " thermograph is used, which supplies 

 continual record of the temperature. 



Two sets of trials were started during the year : the principal ft 

 which 30 chronometers were entered commencing on June 

 while the subsidiary for which there were 12 entries comme: 

 on November 1. Of the 30 chronometers sent for the first 

 only 14 attained the limit prescribed by the Italian Government, 

 brief summary of their performance will be found in Appendix 

 Table III. 



During the year 10 chronometers have been received for t 

 ordinary trials. Of these 1 obtained the A certificate and 3 

 certificates, while 2 failed to pass and 4 are still under examination. 



