46 



REPOKTS ON THE STATE OF SCIENCE. 



Stonyhurst College, near Blackburn. New instruments with quickly- 

 moving record-receiving surfaces have been sent to the Institute y 

 Observatorio de Marina, San Fernando, Spain; the Rio Tinto Company, 

 Limited; Huelva, Spain; Cardiff; and Adelaide. 



West Bromwich, Hill Top. — The instrument established by Mr. 

 Shaw at this station has two pendulums : A, with the boom-point to the 

 east and weight to the west; B, with boom-point to the south and 

 weight to the north. These are suspended from the walls of a cellar 

 excavated in hard gravel. In descending order the strata beneath are 

 105 feet of clay and red sand, 108 feet of clay, clunch, and coal, 60 feet 

 of white rock, 63 feet of rock binds, and 31 feet of coal. The weights 

 are 100 kilos, each. Period 16 seconds. The weight on A is 36 inches 

 from the boom-point, whereas the weight of B is 54 inches from the 

 boom-point. 



Flan, showing 



Fig. 1. 



Both booms are fitted with multiplying levers (ratio, 20: 1) giving 

 a total sensibility for A 0"*1 tilt = 1 mm. amplitude; and for B 0""15 

 tilt = 1 mm. amplitude. 



The records are taken on smoked paper travelling five inches per 

 hour. 



The time is recorded by electric signal each minute, and the govern- 

 ing clock compared with Greenwich daily. Average variation about one 

 second per diem. 



Guildford, Woodbridge Hill. — This instrument was designed and 

 put up by Mr. F. E. Norris. The mast rises 4 J feet above the top of 

 a concrete column, which is sunk 5 feet in London clay. There is a 

 north boom (A) and a west boom (B) recording without multiplying 

 levers. Length of boom, 3 feet; weight at outer end, 100 lb. 1 mm. 

 displacement = 1""88 arc. 



