For proper functioning and maintenance of greenhouses, certain essential greenhouse supplies and equipment are required. The first important supply is the covering or glazing material of the greenhouse since it identifies the effectiveness and success of the greenhouse in terms of plant growing and maintenance. Glass covering provides impact on the aesthetic appearance and permanence of the greenhouse. Some of the weaknesses of glass covering include the disability of retaining heat and low insulating value. It is heavier and therefore needs stronger braces or frames. It is fragile, easy to break and doesn't diffuse light so there's a possibility of plant burning. It also requires contractor installation, which may affect the budget. Plastic covering includes fiberglass, polycarbonate, acrylic sheets, and polyethylene film. Fiberglass is an alternative to glass since it is translucent enough to transmit light. You can purchase them in rolls or ridged sheets. The corrugation grids seal and overlap sides to avoid appropriate temperature inside the greenhouse from escaping. Polycarbonate is the newest covering option, which appears to be stronger and more resistant to environmental impacts like fire. It is available in single, double and triple walled sheets. Single walled coverings are very popular in hobby gardener greenhouse. Double walled is [more..]

The Creator made the water that has turned the wheels of industry from the days of the watermill to the present hydraulic turbine. Man early recognized the potential energy in enormous waterfalls and in the huge waves that crashed against the coastlines of the world, but he has been limited in his efforts to control that power and turn it to his own use. Down by the old millstream may have been a romantic meeting place, but it was also the site of the watermill that ground grain into flour. The flat circular millstones connected with a wheel, which was turned by the current of the stream. Less picturesque but more efficient is the hydraulic turbine, which generates power from dammed-up water. This system is used extensively in North America, Europe and Russia. Two major hydroelectric projects are at present under way in the Dominican Republic. In the central part of the country is being constructed the Tavera complex at an estimated cost of sixty million pesos, while in the south another twenty-two million are being spent on the Valdesia project. Besides providing water for extensive irrigation, it is expected that by 1974 the completion of these projects will make [more..]