■ This issue: welding Austrian trade copying machines irrigation scheme ■ West African construction loading shovels, concrete pumps, road planers, excavator principles. ■ Commercial review: News of contract tenders, financial details, commodity prices and other items of com mercial and business interests to those living or dealing with West Africa ■ Sales Force Control : The tenth part ofa series dedicated to all sales operations striving to achieve maximum results from their existing resources ■ Planning in Developing Countries: A look at the complexities involved in drawing up a workable and successful national development Plan ■ EXPO '78 —A Preview ■ Office Copying Machines : All copying machines are different and careful consideration should be taken when choos ing such a machine. This article looks al some ofthe recent models and gives some useful tips. ■ Solar Energy : Solar energy technology is in the midst ofa world wide revolution — this article looks at recent developments and the prospects for the future. ■ Industrial Diamonds : A look al the properties and uses of industrial diamonds. ■ Irrigation : This article discusses what priorities should be attached to the development of irrigated agriculture and whether Ihe considerable investment necessary is alwaysjustified. ■ Food Processing : This first of a series of articles dealing with food processing machines, deals with those for the all important operation of cleaning the product or material from the farm. ■ West African construction: Calling Nigeria, Wheeled and tracked loaders, Concrete pumps, Road planers, Basic excavator principles ■ Occupational Noise : A look al some of the hearing protectors available on the market and advantages. ■ Testing Trucks for Rough Conditions : A focus on the Scania laboratory and track testing programme, explaining how it helps to ensure that the trucks can with stand arduous operation conditions. ■ Welding of Castings: A look at the important foundry factors to be considered before using cost weid Assembly. ■ Commercial vehicle : More horsepower and a number of driveline changes have enabled the German company Magirus-Deutz to extend its range ofonloff-road tipper-dump truck models. Alan Bunting looks at the latest VlO-engined machines.