X Introduction to the Makerstoun Observations, 1845 and 1840. 



north-east, by an elevated ridge, which forms, to some extent, the northern boundary 

 of the valley of the Tweed. From north, by the east, to the south, the elevation of 

 the horizon, with a slight exception, is under 2° ; from the north to the north-west, 

 increasing from 2° to 4° ; from the north-west to the south-west, the tops of the 

 trees are elevated from 5° to 8° ; and from the south-west to the south the eleva- 

 tion is under 4°. The highest point of the Cheviots, which is 2656 feet above the 

 level of the sea, is about 18 miles to the east-south-east ; it is occasionally referred 

 to in the meteorological remarks on clouds. 



3. The Observatory hill, it is believed, is composed of felspathic trap. The 

 Tweed, immediately to the south, and for a mile to the east and west, flows more 

 or less through this rock, which does not appear upon any part of the hill. The 

 opening for a foundation to the Observatory shewed only masses of rolled pebbles, 

 and boulders of greywacke and trap. 



4. The Observatory is rectangular in its plan, 40 feet by 20 feet internally. It 

 is formed of wood ; copper nails were used ; and iron carefully excluded from every 

 part of the structure. The pillars for the magnetometers and telescopes are of 

 stone, from 22 inches to 19 inches in diameter, and are placed upon excellent stone 

 foundations, completely unconnected with the floor, and every part of the building. 

 By a reference to the plan and elevation, the following details will be understood. 

 (Plate I.) 



There are two windows to the south, with the door between ; and three to the 

 north, which open like folding doors. The dimensions of the principal apartment 

 are, 40 feet long, 12 feet broad, and 12 feet high. The two ante-rooms are each 

 15 feet long, 7^ feet broad, and 12 feet high. The instruments are indicated in the 

 plan as follow : — 



D, The Declinometer. 



^, Its Heading Telescope. 



A, The Azimuth Circle and Transit. 



H, The Bifilar or Horizontal Force Magnetometer. 



t\ Its Reading Telescope. 

 P, A Pillar for a Collimator (not used). 

 V, The Balance or Vertical Force Magnetometer. 

 I, Pillar for the Inclinometer (not used here). 



B, The Standard Barometer. 

 W, The Anemometer. 



W, The Wind-Vane Dial-Plate. 

 T, The Thermometer Case. 



C, The Mean Time Clock. 



n s, The Astronomical Meridian. 

 D t, The Magnetical Meridian. 



