“Are the cross-hairs, as you see them through the telescope, just on the mark?” Rutter demanded.
“Yes, sir.”
“Let me have a look,” ordered Rutter. “A fine, close sight,” he assented, after taking a careful look through the telescope. “Now, take your reading.”
This showed the course by the compass, and was expressed in degrees, minutes and seconds. The poor reading of a course is one of the frequent faults of new or careless engineers.
“Here is a magnifier for the vernier,” continued Rutter, just after Tom had started to make his reading.
“Thank you; I have a pretty good one of my own,” Tom answered, diving into one of his pockets and bringing to light a small but powerful reading glass with an aplanatic lens.
“You carry a better magnifier than I do,” laughed Rutter. “Hazelton, do You carry a pocket glass?”
“Yes, sir,” nodded Harry “I have one just like Reade’s.”
“Good! I can see that you youngsters believe in good tools.”
Tom in the meantime was busy with the vernier of his transit. This is an ingenious device for showing the smaller divisions into which the circles of the compass are divided. Tom quickly jotted down his field note in degrees, minutes and seconds. One chainman now held an end of a hundred-link chain at the nail head on the stake, while a second man started toward the rodman, unfolding the chain as he went.