December 30, 1891.] 



Garden and Forest. 



621 



eight inches of clear stem, the expanded portion measuring 

 two and a half to three inches across, thus making one of the 

 neatest flowers possible for boutonnieres. 



Any one who knows how to grow the common Calla need 

 have no trouble growing this. A light soil, with abundance of 

 well-decayed manure, is preferable, with enough drainage to 

 allow water to flow off quickly. The best plants I saw were 

 growing on a bench near the glass, in a temperature of fifty-five 

 to sixty degrees, and with a light shading even in December. 

 Others were growing in a cooler house, quite exposed, in a 

 drier atmosphere, but did not appear to thrive so well, and 

 were dwarfer, or stunted. The bulblets as they appear about 

 the crowns may be taken off as soon as they develop one or 

 two leaves, and as they need no ripening they will grow at 

 once into neat plants. I believe good marketable plants with 

 one spathe could be grown in five-inch pots. 



Violas. — I lately picked, from under a slight covering of Pine- 

 needles, a bouquet of these in yellow and blue. Unprotected, 

 they would have been all withered by frost ; but why are they 

 not oftener seen in gardens ? They are hardier than Pansies, 

 and will almost take care of themselves. But they become 

 ragged with age, and so it is better to transplant a few of the 

 seedlings, which can always be found about an old bed. They 

 bloom all summer long, and nothing is neater for shallow 

 dishes. 



Wellesley, Mass. T. D. H. 



The Forest. 



The Subjection of Torrents by Reforestation of 

 Mountains. — IV. 



THE TORRENT OF RIOU-BOURDOUX. 



THIS torrent, classed among the incurable ones, and famous 

 for its devastations, was the most powerful of all those 

 which raged in the French Alps. Starting from mountain 

 crests at an altitude of 2,900 meters, it rushed into the Ubaye 

 1,800 meters lower, after a course of three and a half miles 

 with an average pitch of 30 to 100. Its catch-basin is 

 rimmed with ridges of tertiary rock, and at an altitude of 

 2,400 meters it enters the black Jurassic clays. Thus the Riou- 

 Bourdoux, while yet near its source, rushes through deeply 

 cut banks. It receives numerous affluents, most of which are 

 justly entitled to be ranked as torrents already formidable. All 

 these affluents flow between banks cut nearly perpendicularly 

 to a depth sometimes of 100 meters, absolutely bare, bluish 

 black in color and sinister in aspect. Fifteen years ago the 

 Riou-Bourdoux was in full activity, steadily cutting under the 

 foot of its banks and starting land-slides over enormous areas 

 on both shores, which tended to join each other from oppo- 

 site sides, but were quickly separated by the torrent, which, 

 hollowing out its bed between them, carried into the valley 

 prodigious quantities of material. 



The mouth of its "channel of erosion" is found some 1,500 

 meters above the Ubaye, where the torrent spreads out over 

 an immense cone of debris, the base of which is crossed by 

 the national road from Montpellier to Coni. The area of the 

 cone, nearly 600 acres, presents a most desolate aspect, 

 without a trace of vegetation. With each great storm the 

 wash flows over the cone, spreading now over one side, and 

 again over the other. The national road is only a trail across 

 the debris, ceaselessly covered with debris, so that large sums 

 are annually absorbed merely to keep it in passable condition. 

 Such was the situation in 1875, at the time when the works of 

 restoration were declared necessary for the public good. 



To-day the torrent is tamed, and, thanks to operations car- 

 ried out along a definite line and with persistent energy, we 

 are masters of the entire upper basin, where over 3,000 acres 

 of restored forests occupy the degraded lands. The afflu- 

 ents are corrected, the bed is rectified in the channel of ero- 

 sion, and after next year the subdued torrent will flow like a 

 peaceful brook through a definite bed prepared on its cone, 

 leaving an area of 593 acres to be restored to agricultural use. 



In this instance especially was the suppression of the tor- 

 rent a public benefit. It meant the rescue from certain ruin 

 of the territory of an entire commune ; the assured existence 

 of a vigorous population on the frontier ; the protection of a 

 rich valley against deposits which are a destruction to arable 

 lands, security to the threatened city of Barcelonette, and an 

 open highway over the only road to France, an important 

 point in connection with national defense in a notable part of 

 the Alpine frontier. 



THE COMBE OF PEGUERE. 



The ravine opens out at an altitude of over 2,000 meters 

 on the east side of the mountain which overlooks the 



health resort of Cauterets. Long ago subdued by the 

 vegetation which protected its catch-basin entirely, this gorge 

 had again assumed activity, which increased as its basin was 

 more and more denuded by the habitual passing of flocks of 

 goats and sheep. 



In 1884 the danger became more serious ; the security of 

 the thermal springs of Ralliere and others was threatened, 

 travel over the international road from France to Spain became 

 dangerous, and the. safety of Cauterets seemed threatened. 



The alarm among the people in the valley was great, and 

 their authorized representatives hastened to lay their griev- 

 ances before the Minister of Agriculture. 



The peak of Pe"guere, composed of granitic rock, presented 

 this peculiarity, common in all the neighboring moun- 

 tains of the same group, that on the crests the rock is broken 

 in all directions, sometimes to very great depths. The walls 

 of the ravine furnish a striking example of this ; they are formed 

 of blocks of all dimensions, with sharp outlines produced 

 by the dislocation of the primitive rock, and with deep crev- 

 ices between them. They are surrounded by sandy earth and 

 placed in a most threatening state of instability. The least 

 disturbance, the action of gravity alone, may start a movement 

 among these rocks, but water especially brings on the great 

 disasters. In winter, it filters in abundance into innumerable 

 fissures, congeals there, and splits the rock in every direction. 

 In spring, with a sudden melting of snow or with heavy rains 

 the sands which fill the spaces between the blocks are washed 

 away by the waters, and, equilibrium once broken, the move- 

 ment begins. The blocks thus started leap down the smooth 

 steep slope, dashing themselves to pieces, and sometimes bom- 

 barding the establishment of Ralliere or that of Mauhourat 

 with their fragments. Such a destructive force tends to in- 

 crease more and more, and would soon threaten the town 

 of Cauterets if measures prompt and energetic enough to sub- 

 due it were not taken. 



This state of affairs is shown in the report of the survey 

 made in 1884 by the foresters called upon to undertake the 

 work of suppression. It was stated in the first report that in 

 dry times the sands flowed into the hollows of the valley like 

 sand in an hour-glass ; the wind lifted it in clouds ; in times of 

 rain it was borne away by the waters. There was no rest in 

 this ravine ; incessantly some pebble starting dislodged 

 larger blocks, which, like avalanches, descended with a terri- 

 ble crash, shivering the rocks which they struck, and tearing 

 the earth and trees as they bounded along. 



The most intrepid mountaineers would only venture to cross 

 the mouth of the Combe on a run, while into its depths they 

 never thought of penetrating, so constant was the peril from 

 falling rocks, which the slightest touch might dislodge. 



Of course no work could be done here during the bathing 

 season, the operations were restricted to the first days of spring 

 or the last days of autumn. The construction of a system of 

 walls on such a steep slope was not practicable, on account of 

 the expense which their great number and size would in- 

 volve. 



The problem consisted essentially in retarding the motion 

 of the more or less earthy sands, which keep the blocks in 

 unstable equilibrium. Observation of the local climate, to- 

 gether with the nature of the soil, furnished a very simple and 

 economical plan of solution. The plan was : (1) To clear the 

 slopes of all loose blocks whose fall seemed imminent ; (2) To 

 reclothe, as far as possible, all the sands "with a mantle of 

 vegetation formed by plats of grass, and to calk, so to speak, 

 all the spaces between the rocks considered reasonably firm ; 

 (3) To construct retaining walls of dry rock wherever the ac- 

 cumulated rocks left no chance for the grass to support 

 itself. 



This operation would leave no work of man visible except 

 the retaining walls ; the remainder would be transformed into 

 a mountain sod, from which would emerge here and there 

 portions of the protected rocks. 



The execution of the work was exceptionally difficult ; the 

 necessity of working in the Combe only at rare times in order 

 to avoid all danger to the thousands of bathers at the springs 

 below ; the total absence of roads and paths in the steep 

 slopes ; the lack of workmen accustomed to the perils which 

 were to be constantly faced ; the distance which it was neces- 

 sary to transport sods ; the danger from dropping the smallest 

 stone in building the walls, lest it start an avalanche of rock ; 

 the lack of all shelter for the workmen ; the difficulty of pro- 

 curing water ; constant dangers to the lives of the workmen — 

 all these were discouraging conditions. But the workmen, 

 following the example of their chiefs little by little, grew 

 courageous and confident, and finally conquered all opposition. 



The result of the first five campaigns exceeds the most san- 



