I have just been speaking to my brother, Sturton, concerning some
rather alarming revelations. That, however, is not the topic for
It transpires that Sturton had lunch with our intercalary twin shortly
before the latter departed for Indonesia in search of the Javan
Large-eyed Water Bat. He (that is, our intercalary, not
Sturton, nor even the Javan Nocturnal Large-eyed Water Bat) is
accustomed to travelling light in difficult terrains, and has over the
years taken with him many ingenious devices of his own
Those of you who know our twin will recall that he wears a
monocle (since he is slightly hard of seeing in his left eye), and the
instrument which he showed Sturton at first gave the appearance of
being merely a monocle held in place with a stout headband. It
looked rather ridiculous, although less so in the context of the
As is usually the case with him, however, all was not as it first
appeared to seem.
As you will of course know, a Galilean telescope consists of two
lenses, set at either end of a tube. The far lens is gently convex,
while the nearer lens is somewhat stronger and concave.
You will probably also know that, when two lenses are placed very
close together, their combined refractive power approximates to
the sum of their individual powers. Thus, a weak convex lens
placed on top of a strongly concave one behaves very much like a
single weakly concave lens.
It was this arrangement of superposed lenses which constituted our
twin's strange monocle, and which corrected his near sightedness
sufficiently for him to choose the wine at the dimly-lit table.
Over dessert, however, the true brilliance of this creation was
revealed. With a flourish, our twin reached up to his eye and
gripped the forwardmost edge of his compound monocle. Extending
his arm, he not only ignited his shirt-sleeve on the candle, but also
revealed that the front lens of his monocle could be extended on
two stout cords which had hitherto been concealed in the headband.
The resulting pair of lenses, now held precisely 50cm apart by the
cords, acted as a near-perfect Gallilean telescope, of sufficient
power for him to determine that the same wine was a full nine
pounds cheaper in the Ethnic Australian Bistro several hundred yards
down the road.
As we speak, our intercalary twin is probably scrambling along some
Javan riverbank, wielding his machete with one hand whilst using
this uniquely portable and monomanual telescope to scan the
skyline for his quarry.
In case he does not return, I am posting this idea here lest its secret
be lost with him.