A swimmer’s dictionary

When swimming across a deep lake you might want to pause and tread water. If, when you do this, your feet suddenly dangle down into much colder waters it can somehow make palpable all the dark and terrible dangers that your imagination can conjure from those inky depths. Instinctively you pull your feet up, and without a steely grip on your nerves this retraction can quickly turn into a full retreat, sending you tearing back to shore with the sum of your irrational fears in dark, sharp pursuit. Or perhaps this just happens to me?

As well as highlighting my cowardice this experience nicely illustrates the thermal stratification of lakes, which happens in summer and winter, when distinct zones of temperature form at different depths. Epilimnion is the name given to the uppermost layer of water, which can be a startlingly different temperature to the one just below.

Water is densest at 4˚C and so a layer at this temperature is often at the bottom of a lake. In the winter the layers above become progressively colder as you go up, with ice, being less dense than liquid water, forming on the surface. In summer the strata are reversed with the warmest water at the surface and the temperature dropping as you go deeper. Spring and Autumn are periods of transition between these two different states of layering during which the waters are thoroughly mixed up, which helps redistribute oxygen and nutrients throughout the lake.

Water flows, trickles and percolates through the peat bogs of Lewis under many guises. It flows out from lochs as a “feadan”, the same name as is given to the bagpipes’ chanter, through which the melody flows; it cuts twisting veins through the peat and is named “faith”, Gaelic for sinew. When it pools it might be a deep “linne”, a shallow “glumag” or a boggy “botann”. Where a stream runs in a channel so slender and overgrown that its presence is only given away by the gentle purl of running water it takes its name from the Gaelic for that murmuring sound: caochan, a word that also describes the bubbling sound of fermenting worts and the eddying of air and water.

This term appears in the Dictionary of Newfoundland English published in 1982, which is a particularly rich resource of words from the fishing communities of northeast Canada. Many of these communities were established by immigrants from Britain, who brought their language to the new worlds with them and in many cases the words that dwindled in their place of origin were kept in use much longer in their adopted homes. One of these linguistic expatriates is “wellum”, sometimes spelled “willem”, a word for the radiating ripples set of by a surfacing fish. I have seen many wellums but hardly ever seen the fish that made them. They are what you see when you turn to the sound of the plop; they are what the quivering branch is to the birdwatcher and the swaying curtain of grass to the deer-hunter. They are a sign of absent presence.

When the full moon hanging low over the sea casts a light from the horizon to the shore, this avenue of light is called a “moonglade”. You might also catch a moonglade on a lake but only if there are enough waves to throw the light around since a broken surface is essential to stretch the reflections into a glittering path. The term seems to originate from 19^th century New England and was brought to wider attention by Thomas Wentworth Higginson, fervent abolitionist, campaigner for women’s suffrage and the commander of the first regiment of freed black slaves in the US civil war: “There is no Americanism more graceful than the word ‘moonglade’. It is applied along our New England coast to that path of light which lies beneath the moon upon the sea, and which appears to slope down from the horizon to the place where the each observer stands. This broad and luminous track is as distinct from the expanse around it as is any path through the forest from the surrounding trees; and both alike offer a vista for the imagination as well as a delight to the eye.”