英文翻訳をお願いします。
Visual signalling was used as a substitute for line communications but some short-range (7,000-yard (6,400 m)) wireless transmitters were introduced; weighing 101 pounds (46 kg), needing four men to carry and considerable time to set up, they proved of limited value. Artillery boards came into use, which had blank sheets with a 1:10,000 scale grid in place of maps, datum shooting was used to check gun accuracy from 2–3 times a day and better calibration drills and meteor (weather) telegrams were announced. The tactical role of artillery was defined as, the overpowering of enemy artillery, the killing or incapacitating of enemy infantry and the destruction of defences and other obstacles to movement. Barbed-wire was the most difficult obstruction to tackle and 1,800–2,400 yards (1,600–2,200 m) was the best range for cutting it with 18-pdr field guns (with regular calibration and stable gun platforms), conditions which were not always met.
