The Entente countries were slow in adding meteorological units to their armies, but their civilian meteorological services were utilized to the utmost for military purposes from the beginning of the war. They at first worked under difficulties arising from the cessation of the customary weather reports from central Europe, but, to offset this disadvantage, the weather map was expanded in other directions, the number of daily hours of observation was increased, and eventually the forecasters in London and Paris acquired much better facilities for making their predictions than they had enjoyed in time of peace. The supply of weather information to the public was suspended, and great precautions were taken to prevent the reports of the Allied services from being utilized by the enemy. The German meteorologists were seriously hampered by the lack of reports from the westward. It has been asserted that such reports were sometimes obtained by radio from submarines stationed off the coast of Ireland, but such a service, if it existed, must have been fragmentary and unsatisfactory. That the Germans made many mistakes in their attempts to infer the atmospheric conditions over the British Isles from the limited weather map at their disposal is proved by the fact that their airships frequently crossed the Channel when, with an ampler knowledge of impending weather, they would certainly have remained at home. Several Zeppelins came to grief in the course of these ill-timed raids. One of the interesting routine duties of the British Meteorological Office during the war was to draw the weather map for a given moment as the Germans would probably draw it, with their curtailed set of telegraphic reports, and then predict the German prediction! In the spring of 1915 a small meteorological section was organised in the British Army, and attached to the Royal Engineers. This force was afterward enlarged, and provided units for service on several battle fronts. The British also developed a naval meteorological service, which had existed in embryo before the war, and, eventually, a special meteorological service for the Royal Air Force. Analogous services were organized by the French and the Italians. The United States Army and the United States Navy both established meteorological services not long after this country entered the war. The former was attached to the Signal Corps, and was partly officered and recruited from the Weather Bureau. A training school for army meteorologists was opened at College Station, Texas. Upward of 300 men were given instruction in this school, and most of them were sent overseas. The naval meteorological service was headed by the director of Blue Hill Observatory, and the junior officers received special training at that institution.