Bertha's Visit to Her Uncle in England; vol. 2 [of 3]

by Mrs. Marcet

But what interested me much more than all her snuff and tobacco, was the account she gave of some dear little green humming-birds, that used constantly to build amongst the flowers of a convolvolus that grew against the house near her window. She took the greatest pleasure in listening to their little feeble notes, and in watching their rapid motions and all their habits. They were of a smaller species than any of our little Brazilian beauties; and she says the eggs were actually just the size of coriander seeds!

14th.—As I was curious to see the effect of frost on a very wet soil, Frederick and I went this morning to a spot in the low fields, where we knew it was always swampy. We observed that, as we walked there, the ground crackled, and sunk a little beneath our feet; so Frederick went for a spade, and we gently raised up one of the large lumps between two of the cracks. We found very near the surface a thin crust of ice, and under that a forest of minute columns of ice, standing close together like a fairy palace, with rows in it of clustered pillars; for each column was in reality composed of several lesser ones, not thicker than large pins. You cannot think, mamma, how pretty they were.

When we raised one of these cluster columns with its capital of earth, it separated quite easily from the ground beneath it; but still a thin film of earth remained sticking to the bottom of the column. Frederick brought home a lump of these icy pillars on the spade, and my uncle laid aside his letters, to shew, he said, how much pleasure he felt when he saw us in pursuit of knowledge. As soon as he looked at our pillars, he said, “In that sort of spongy soil where you found them, these icy crystals are formed so immediately under the surface, that only a thin crust of earth remains over their tops; and the film of clay, which sticks to the bottom of the column, shews you that the frost has not penetrated below it, but that the earth beneath continues soft. I see you are looking at those marks across the pillars: break the column at one of the marks.”

I did break one, and found exactly such a film of earth between the two parts of the column, as that which was on the bottom of it. I asked how could earth get into the middle of the crystal?

“Each division,” said my uncle, “shews a separate crystal—each crystal was formed in one night,—and the number of joints or interruptions in the column shew how many nights we have had frost.”

I reckoned four divisions in each column; the uppermost was the longest, the next shorter, and so on; and I pointed out that circumstance to my uncle.

“That,” said he, “is easily accounted for; whatever quantity of moisture there was in the ground at first, there must have been less and less every succeeding night, and the length of the columns therefore diminished each night in the same proportion.”

In a short walk that we afterwards took with my uncle, he observed, as we passed the garden of a small cottage on the border of the forest, that it was late to see carrots still in the ground; and Frederick remarked that the earth looked cracked and swelled round them. My uncle asked leave of the cottager to go into the garden, and there we found that several carrots were actually pushed upwards by the icy columns, the tops of which adhered to the crown of the plant, from which the leaves spring. As the additional joints of the columns had formed, they had acted with so much force, as, in some cases, to break the small fibres by which the root is held in the ground; and in others even the end of the tap root of the carrot was snapped asunder.

I took an opportunity of asking my uncle if there are any spicula in an icicle, which looks so transparent and smooth.

He explained to me, that an icicle assumes its smooth conical form from the gradual congealing of the water as it flows down the surface of the icicle. When broken across, he shewed me that it was somewhat radiated in the structure, as if the spicula arranged themselves round the axis; and he added that if I examined a flake of snow, I might see the same appearance.