,-fl6 ' . ... ACCOUNT OF EXPERIMENTS^ ^^ 



yj.iiQ. The next object (and this one of the greatest importance) was to 

 contrive a very accurate scale, aa little liable to alterations as possible. 

 This was measured from a standard scale belonging to Major Lambton-j 

 graduated in the temperature of 61^, transferred by himself on a brass 

 ruler, originally also a standard scale, but since disfigured. 



11. Having fixed a plate of glass, with nails and bees-wax, against the 

 wall, and secured the whole by pasting paper over the edges, I then drew, 

 with great care, on a slip of paper (fixed on the field of the glass) a six 



Inches diagonal scale, directed downwards. Then, taking the length of the 

 stahdard scale with beam compasses, I applied one of the points to the 

 three inch line, letting the other hang downwards. ' 



12. Under this, I fixed another plate of glass, by the same process |: 

 and where the inferior leg of the compass fell, I drew an horizontal Tme^ 

 which being made equal to the upper dimensions, terminated the scale. 

 It requires rib further detail, to acquaint the reader, how, by means of other 

 plates of glass, all unconnected^ it was lengthened or shortened at pleasure ; 

 I shall only add,: that on repeated trials, during- more than one month, it did 

 not vary in any ^perceptible degree ; and with it I could measure to —o-^, 

 parts of an inch, and estimate still nearer,. -• - =v.- ,....., . a,. , / 



13. Before and after every experiments I measured the pendulum^ 

 in the following manner, noticing each time the thermometer, I applied 

 firmly the sliding leg of the compasses, to the lower surface of the iron 

 head ; and then caused the ball to swing gently over the inferior or ad- 

 justing leg, so as just to touch it. The least friction was easily discern- 

 ibie, by the hand holding the beam ; and I carefully examined, with a 

 magnifying lens, whether the upper leg was close in contact with the iron 



