STATIONS OF OBSERVATION:--Pickets--False Picket--Permanent
Stations--Referring Object--Heliotrope--Heliostat--Heliograph
Signalling--Morse Alphabet--Night Lights--Oil Lanterns--Magnesium
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CHAPTER XVII.
Surveying and Levelling Instruments, Theoretically and Practically Described. For construction, qualities, selection, preservation, adjustments, and uses; with other apparatus and appliances used by civil engineers and surveyors in the field. · 第 17 / 26 章