such business firm
as that of the Clarks ever existed in this country or any other.
Here is an example. Shortly before the time of Struve's visit,
I had arranged with them for the construction of a refined and
complicated piece of apparatus to measure the velocity of light.
As this apparatus was quite new in nearly all its details, it was
impossible to estimate in advance what it might cost; so, of course,
they desired that payment for it should be arranged on actual cost
after the work was done. I assured them that the government would
not enter into a contract on such terms. There must be some maximum
or fixed price. This they fixed at $2500. I then arranged with
them that this should be taken as a maximum and that, if it was
found to cost less, they should accept actual cost. The contract
was arranged on this basis. There were several extras, including
two most delicate reflecting mirrors which would look flat to the
eye, but were surfaces of a sphere of perhaps four miles diameter.
The entire cost of the apparatus, as figured up by them after it was
done, with these additions, was less than $1500, or about forty per
cent. below the contract limit.

No set of men were ever so averse to advertising themselves.
If anybody, in any part of the world, wanted them to make a telescope,
he must write to them to know the price, etc. They could never be
induced to prepare anything in the form of a price catalogue of the
instruments they were prepared to furnish. The history of their
early efforts and the indifference of our scientific public to their
skill forms a mortifying chapter in our history of the middle of the
century. When Mr. Clark had finished his first telescope, a small
one of four inches aperture, which was, I have no reason to doubt,
the best that human art could make, he took it to the Cambridge
Observatory to be tested by one of the astronomers. The latter
called his attention to a little tail which the glass showed as
an appendage of a star, and which was, of course, non-existent.
It was attributed to a defect in the glass, which was therefore
considered a failure. Mr. Clark was quite sure that the tail was
not shown when he had previously used the glass, but he could not
account for it at the time. He afterwards traced it to the warm air
collecting in the upper part of the tube and producing an irregular
refraction of the light. When this cause was corrected the defect
disappeared. But he g