It is essential for the production of good cement, that the mixture of the ingredients be complete.
Prices of the various parts of the Dioptric Apparatus.
The expense of the various parts of the Dioptric apparatus is as follows: Great lens of first order, L.58 (8 of which are required); pyramidal lens and mirror, L.14, 12s. (8 of which are required); catadioptric cupola, L.480; catadioptric rings below lenses, L.360; pannel of dioptric belt for fixed light of first order, L.56 (of which 8 are required for the whole circle); apparatus of fourth order, for a fixed light, for whole horizon, L.128; apparatus of sixth order, for whole horizon, L.44. The expense of the mechanical lamp of the first order with four wicks, as made for the Scotch Lighthouses by Mr John Milne of Edinburgh, is L.30.
Diagrams illustrative of the [Table], Appendix, No. IV.
Fig. 114.
Fig. 115.
Fig. 116.
