434 



THE IRRIGATION AGE. 



it is best to have these located by an engineer or some 

 one of experience in this work. Some of the common 

 mistakes in putting in lateral ditches are to put them on a 

 grade that is too steep, and to put them too far apart. 

 Ordinarily, lateral or distribution ditches ought to be 

 placed from fifty to sixty feet apart, and the fall should 

 not greatly exceed one inch to the rod. In the case of a 

 field with a definite side hill slope, the laterals should run 

 around the side of the hill. Laterals are commonly put 

 in with a double mold board plow. When the fall will 

 permit, it is obviously best to make them straight. This 

 makes for ease in cutting and handling the crop. The 

 machinery does not strike the ditches at different angles. 

 However, this advantage is not sufficient to offset the seri- 

 ous disadvantages from the washing of the ditches and the 

 improper distribution of the water where ditches are on 

 a grade that is too steep. 



In order that the water may be turned out of the 

 ditches at the proper places, diversion dams are put in 

 every sixteen to twenty feet. When the ditches are fresh- 

 ly made, these dams may be of dirt gathered in the bottom 

 of the ditch. After the alfalfa becomes well established, 

 dirt dams are not practicable and manure dams are gen- 

 erally used. These dams consist of piles of manure in the 

 bottom of the ditches, and this is spread over the field 

 as the darns are removed during irrigation. In some sec- 

 tions canvas and metal dams are used. The canvas dam is 

 made by attaching heavy-weight canvas to a cross piece 

 which is wide enough to go across the ditch. The canvas 

 is long enough so that it lies along the bottom of the 

 ditch for six or eight feet, and is held down by a few 

 shovelfuls of dirt thrown on it. This form of dam makes 

 for a relatively small amount of shovelling, and seems to 

 be gaining in popular favor. Metal dams are usually 

 made of galvanized iron and shaped so that they fit the 

 bottom of the ditch to a certain exttent. A strong cen- 

 tral stake is provided and the dam is driven down into the 

 ditch. 



Turning from a consideration of the preparation to 

 the actual irrigation, two questions stand out as of chief 

 importance. These are: When should alfalfa be irrigat- 

 ed, and how much water ought to be used? As to the 

 proper time of irrigation, the common practice includes 

 irrigation before the first crop is cut, or irrigation for the 

 first time after the first cutting of hay has been removed 

 from the field. Where there is a fair amount of rainfall 

 during the early summer, and where there are apt to be 

 showers while the first crop is curing, it is usually best to 

 add no irrigation water until this crop has been removed 

 from the field. The irrigation can then be given quickly 

 to start the second crop. Where springs are dry, and espe- 

 cially where good curing weather may be depended on at 

 haying time, it insures a prompt start in the second crop 

 if the field is irrigated ten days or two weeks before it is 

 ready for the first cutting. After the second crop has 

 been removed, the field is again irrigated. In localities 

 where four crops are harvested, irrigation is again neces- 

 sary after the third crop. At the higher altitudes and un- 

 der other conditions where curing is slow in the field, no 

 fourth crop is cut, but instead the fields are pastured. In 

 this case irrigation is not practiced after the third cutting. 

 The question of the amount of water to use merits 

 careful consideration. It might safely be said that in the 

 majority of cases irrigation farmers are using much more 

 water than is necessary. The truth of this is shown by 

 the increase in acres ruined by alkali, and by the swampy 

 condition which is noted on the lower lands in irrigated 

 sections. 



If we compare the natural precipitation of irrigated 

 areas with that of humid sections where no irrigation is 

 practiced, we will find that the difference does not exceed 

 ten to fifteen inches a year on the average. In many hu- 

 mid localities the crops would be benefited by a little more 

 rainfall, so we must naturally expect to more than make 

 up this difference. If water equivalent to fifteen or twenty 

 inches should be added at the proper time, it ought to fully 

 supply the amount needed for the growth of the crop. A 

 study of the duty of water or of the amount of water 

 which is being used from many of the streams in the 

 State of Montana shows that the amount taken out during 

 the irrigation season is sufficient to cover the irrigated 



(Continued on page 441.) 



THE MANUFACTURE OF INDIA RUBBER. 



By Dr. Leonard Keene Hirshberg, A. B., M. D. (Johns 

 Hopkins.) 



In a historical volume written at Madrid in 1601, de- 

 scribing the discovery of America by the Spaniard of 

 Castile in 1^ and the following year one, Antonio de 

 Herrara Y Tordesillas, mentions the fact that the Haytians 

 played a ball game with gun balls. This is the first ex- 

 ample in literature of any suggestion of India rubber. 

 This same writer describes the Mexicans as making slits 

 in tree<: to permit the flow of a pleasant smelling, milky 

 gum. Juan de Forquemanda, in his book: "The Indian 

 Konarchy," published in 1615, described those trees ac- 

 curately as rubber trees, and states that the Indians used 

 this "elastic" gum for medicine and the Spaniards used 

 it for "waterproof cloaks." 



Lacondamine sent some of the dark gummy caoutchouc 

 from Brazil to the Paris Academy in 1736. The Indians 

 had long known its waterproofing powers, and called the 

 gum of the Hevea tree "Cahucha." Fusset Aublet, a 

 French botanist, discovered the same tree in 1762 in 

 French Guiana, while three years later M. Coffigny found it 

 in the Island of Madagascar. 



Chemists sought with great difficulty some sort of 

 solvent for this, but not until 1761 was it accomplished. 

 Herissont and Macquer then dissolved caoutchouc in oil 

 of turpentine, rectified over lime, and obtained a mas& 

 that allowed the rubber to regain its elastic state. Ether 

 was also usi-d. 



Priestley, the great discoverer of oxygen, in 177O 

 found that rubber made a good eraser for pencil marks. 

 Magellan then two years afterward incited the French 

 to use rubber commercially and its price was $5.00 an 

 ounce. 



In 1798 Mr. J. Howison discovered a rubber tree 

 (Urceola elastica) in Penanh province and Dr. Roxburgh 

 announced another tree (ficus elastica) in Assam province. 

 Samuel Peal in 1791 had already taken out the first 

 patent in connection with rubber "for the application of 

 dissolved rubber to waterproofing." Twenty-nine years 

 later a second equally useless patent was obtained by 

 Thomas Hancock, April 29, 1820. In 1823 Charles Macin- 

 tosh received the patent on waterproofing fabrics by dis- 

 solving rubber in coal oil and built the first factory in 

 Glasgow, removed later to Manchester. This firm, C. 

 Mackintosh & Co., had Messrs. Birley as partners. The 

 third and fourth generations of the Birleys are still man- 

 aging this, the largest factory making raincoats, in the 

 world. 



Until 1823 rubber was imported in the shape of figures 

 and bottles. No uniformity in thickness was possible. 

 True, Hancock had, in 1826, made a hand-machine to 

 macerate the rubber, but this machine could only squeeze 

 one pound at a time. 



In 1827 Hancock moved into a larger house in Gos- 

 well Road. Here a horsepower mill, using large iron 

 rollers, macerated the rubber while raw and hot. A rough, 

 corrugated sheet of rubber emerged from the rollers and 1 

 dried very easily. The only difference between the rollers 

 in use today and those used in 1826, is the size. The 

 sheets then weighed about fifteen pounds. Now they 

 weighed more. Garters, bracers, knee caps, bandages and 

 suspenders were all made by Hancock. As early as 1823 

 he made billiard table cushions and in 1826 was manu- 

 facturing driving belts. He gave Macintosh royalties for 

 the use of his patent. 



Hancock made air beds, cushions, life preservers, div- 

 ing suits and started a branch factory in 1828 in Paris. 

 In 1830 he merged with Mackintosh & Co., but maintained 

 separate factories. 



The fact that all articles made then would not stand 

 the stress of heat and cold lead a German chemist, Pro- 

 fessor Ludersdorf, in 1832 to the discovery that sulphur 

 mixed with rubber dissolved in turpentine removed all 

 viscosity from the rubber. Here he stopped. 



Then in 1839 Nelson Goodyear, an American, solved 

 the riddle of the rubber question. He discovered how to 

 produce rubber objects that would withstand all extremes 

 of cold and heat. Nathan Haysard, his friend and partner, 

 one day accidentally dropped some rubber mixed with 

 sulphur upon a heated stove. When he picked it up it 

 was noticed that the sulphur was absorbed by the rubber, 



