error in delivery is calculated for full power, two-thirds power, one-third power, and idling or fifteen per cent of full power.

Figure 27 shows graphically the results of the calculations in Figure 26. The curves for the per cent error in delivery for the Bureau Type fuel pump given on page 67 of the February, 1925, JOURNAL are superimposed on those for the herein calculated cam profile. As is seen accuracy in delivery for sinall clearance errors for the given cam profile compares very favorably with the accuracy for the reciprocating linkage of the Bureau Type fuel pump. The same accuracy is obtained at full power and about twice as great accuracy at idling power. This makes obvious the fact that for a given average lift the accuracy of delivery for small clearance errors for a cam controlled suction valve can be made to exceed the accuracy of a reciprocating controlled suction valve. In fact, the accuracy of the cam control can be chosen at will, whereas the accuracy of the reciprocating control for a given maximum lift is fixed by the stroke of the pump.

NOTES.

THE PROGRESS OF AERONAUTICS.

FIFTH ANNUAL REPORT OF AERONAUTICAL RESEARCH COMMITTEE.

The report of the Aeronautical Research Committee for the year 1924-1925 has just been published and contains a great deal of interesting matter. It is pointed out that at the end of the financial year a reconstitution of the Committee took place, the new terms of reference being as follows:

"(1) To advise the Secretary of State on scientific problems relating to aeronautics. (2) To make from time to time recommendations to the Air Council as to any researches which the Committee consider it desirable to initiate, and as to any matters referred to them by the Council. (3) To supervise the aeronautical researches at the National Physical Laboratory initiated by them, and, if requested to do so by the Air Council, any other researches connected with Aeronautics. (4) To make an annual report to the Air Council of the research work which the Committee consider should be undertaken at the National Physical Laboratory, or elsewhere, together with an estimate of expenditure at the National Physical Laboratory. (5) To investigate the causes of such accidents as may be referred to them by the Air Council, and to make recommendations as to the prevention of accidents in the future. (6) To promote education in aeronautics by cooperating with the Governors of the Imperial College and in any other way within their power. (7) To assist with advice any research carried out by or on behalf of the Aeronautical Industry, and to make available any information of value to the Industry so far as is compatible with public interests. (8) To make an annual report to the Secretary of State for Air." In the previous terms of reference the Committee were instructed to advise on scientific and technical problems relating to the construction and navigation of aircraft. This change, it is pointed out, has been made possible by the reorganization at the Air Ministry at that establishment, which formerly dealt with technical development and research and as a further consequence the Air Council has decided that future membership shall be confined solely to members appointed in virtue of their scientific standing, rather than as representatives of definite interests.

A. R. C. AND AIRCRAFT INDUSTRY.

The report points out that contact between the Committee and the Aircraft Industry will still be maintained by the following arrangements:-"(a) Annually, before the program of research for the ensuing year is decided upon, a joint meeting of the Aeronautical Research Committee and the Industry will take place, at which the carrying out of particular researches during the ensuing year will be freely discussed. After this joint meeting has been held, the Aeronautical Research Committee and the Society of British Aircraft Constructors will forward their respective proposals for research to the Air Council, who will decide upon the program for the ensuing year. A copy of the decisions will then be forwarded to the Aeronautical Research Committee and the Society of British Aircraft Constructors. (b) Six months after the program has been decided upon a second joint meeting of the Aeronautical Research Committee and the Society of British Aircraft Constructors will take place, at which the progress of the last six months

will be reported and a discussion will ensue. As a result of this second meeting, the Air Council will decide if any modifications of the annual pro

gram are necessary.

The Committee welcomes the grant of £1500 made available by arrangement with the Air Ministry for the purpose of grants to individual research workers. The amount of this grant exceeded by £500 that allowed in the previous year, in order that funds might be made available for special experiments on light aeroplanes. Grants have also been made for work on experimental research on redundant structures, on wind tunnel and theoretical research on skin friction, and on theoretical research on the problem of control at low speeds.

The report states that in addition to the provision of the above grants, some work financed by the Department of Scientific and Industrial Research "has been carried out on elasticity and fatigue at Oxford University" (this is the official wording!), and a program of investigation on single cylinder internal-combustion units is in hand at the Universities of Cambridge, Durham and Manchester.

The scheme of the Sub-Committees and Panels directing the work in detail is under consideration by the reconstituted Committee. It is stated that during the past year no new problems have been referred to the Meteorology Sub-Committee or to the Fire Prevention Committee, and these Sub-Committees have consequently not met. Under the new terms of reference the Air Inventions Sub-Committee will no longer exist, the work being carried out in its entirety by the Air Inventions Department of the Air Ministry.

Reference is also made in the report to the work of the Airship Co-ordinating and the Structures Sub-Committees.

The Committee point out that the new arrangements to which reference was made last year have resulted in the publications of the Committee being issued more rapidly and brought up to date. Not only are the individual Reports and Memoranda issued within a few weeks of their approval by the Aeronautical Research Committee, but the annual volumes of collected technical papers for past years are now on sale.

Equipment for Experimental Work-The Committee did not make any new proposals this year for increasing the equipment at the National Physical Laboratory, except in connection with certain proposals for a new high-speed tank. It is considered important that approval for the construction of this tank should be given, as with the progress in seaplane development it is imperative that equipment should exist by means of which comparative tests may be carried out at speeds considerably greater than those now possible with the existing equipment at the William Froude Tank, and it is thought that better progress in seaplane development will result therefrom as no means exist at present for making model experiments on a highspeed seaplane.

Progress of Research-The report points out that in two directions a substantial stage in progress has been reached. One of these is the problem of stalled flight, which with the completion of the first flight experiments on the slot-and-aileron control, is now emerging from the pioneer stage. The other promising advance has been made in the course of investigation on elasticity and fatigue.

AERODYNAMICS.

Research upon the control of stalled aeroplanes has gone steadily forward, and the conclusion is formed that conventional aeroplanes when stalled are defective in two respects-they have insufficient rudder power, and the ailerons when applied cause the aeroplane to turn and, by doing so, neutralize their direct effect on roll. It has been found that either an increase of