The British Expeditionary Force was ready for service abroad, and it fell to the Naval Air Service to watch over its passage across the Channel. A regular patrol between Westgate, close to the North Foreland, and Ostend was maintained by seaplanes, following one another at intervals of two hours. On the 13th of August a temporary seaplane base was established at Ostend under the command of Flight Lieutenant E. T. R. Chambers, but on the 22nd of August, when the expeditionary force was safely landed and the occupation of Ostend by the Germans seemed imminent, the base was withdrawn, and the men and stores were taken back to England. An airship patrol of the Channel undertaken by airships Nos. 3 and 4 (that is to say, by the _Astra-Torres_ and _Parseval_) began on the 10th of August, and was continued throughout the month. The average time of flight of a seaplane on patrol was about three hours, of an airship about twelve hours, so that the airship, which could slacken its speed and hover, had the advantage in observation. The chart printed on p. 363 illustrates the patrols carried out by the two airships on the 13th of August 1914. Here are copies of their logs for the day: '_Log of No. 3 Airship, 13th August 1914._ 7.10 a.m. Rose. 7.37 Passed Sittingbourne. 7.45 Passed Teynham Station. 7.50 Passed Faversham. 8.20 Passed Canterbury. 9.0 Passed Coastguard Station. 9.49 Sighted No. 4 Airship. 10.41 Sighted seaplane on starboard quarter. 5.50 p.m. Altered course for Coastguard Station. 6.25 Coastguard Station. 6.54 Faversham. 7.4 Sittingbourne. 7.34 Landed. '_Log of No. 4 Airship, 13th August 1914._ 7.40 a.m. Left Kingsnorth. 9.28 Passed Coastguard Station, shaped course for Calais. 10.35 Shaped course for Dover. 11.25 Shaped course for Calais. 11.35[5] Broke one blade of port propeller, rendering it necessary to change two for new blades. 12.55 p.m. Proceeded to Calais. 1.40 Shaped course for Dover. 2.12 Course as requisite to arrive at Calais. 2.52 " " " " " " Dover. 3.20 " " " " " " Calais. 4.00 " " " " " " Dover. 4.45 " " " " " " Calais. 5.45 " " " " " " Deal. 7.30 Arrived at Kingsnorth. 7.53 Landed. [Footnote 5: 'Off Dover at 11.35 a.m. one blade of the port propeller burst and flew off, narrowly missing damaging the rigging near the envelope. We were able to fit two new blades while under way and continue the patrol. This took one hour and twenty minutes.'] [Illustration: Airship Patrol. 13th August, 1914.]