After a time we drew near the road, and as we did so we heard the
clatter of hoofs and saw through the tree stems three cavalry soldiers
riding slowly towards Woking.  We hailed them, and they halted while
we hurried towards them.  It was a lieutenant and a couple of privates
of the 8th Hussars, with a stand like a theodolite, which the
artilleryman told me was a heliograph.