dangerous occurrences . to provide fuller information about certain types of dangerous occurrence , section 65 of the factories act , 1937 , requires notification of certain specified occurrences to H.M district Inspectors of factories , whether or not they result in injury . appendix 20 gives figures of dangerous occurrences reported in 1960 ; the types of occurrence which have to be reported are set out in the heading to the appendix . the total number of dangerous occurrences reported during the year was 1,409 , an increase of 111 over the total for 1959 . however , the number of notifiable accidents associated with occurrences fell from 252 ( 31 of them fatal ) in 1959 to 245 ( 22 fatal ) in 1960 . the main increase in the numbers of occurrences reported occurred in the category of those due to the collapse or failure of a crane , derrick , winch or hoist , where there was an increase of almost one-third from 335 to 438 . this increase was common to factories , docks , and building operations . industrial health . an analysis of cases of industrial disease or poisoning notifiable under section 66 of the factories act , 1937 , or under section 3 of the lead paint ( protection against poisoning act ) , 1926 , together with comparable figures for earlier years , is given in appendix 21 . the total number of cases notified during the year was 569 , compared with 532 in 1959 ; the number of deaths remains unchanged at 10 . cases of chrome ulceration increased from 192 to 298 , but reportable cases of epitheliomatous ulceration decreased from 226 ( nine of them fatal ) in 1959 to 173 ( six fatal ) in 1960 . the total of 19 cases of this disease due to mineral oil is the smallest number in that category for the last 10 years . appendix 22 records the number of accidents involving gassing in 1960 , together with the figures for previous years . both the total number of accidents ( 222 ) and the number of deaths ( 20 ) were greater than in the previous two years . those of the above accidents which involve special circumstances or matters of particular medical interest are discussed in greater detail in the industrial health report for 1960 . appendix 23 records the numbers of statutory examinations carried out by appointed factory doctors under the factories acts special regulations , and the numbers and circumstances of voluntary medical examinations . appendices 24 and 25 set out the number of statutory examinations of young persons for certificates of fitness carried out by appointed factory doctors , together with the causes of rejection . these examinations numbered 500,984 in 1960 , an increase of 21,962 on the previous year . there were 283,906 examinations of male young persons ( an increase of 19,706 ) and 217,078 examinations of female young persons ( an increase of 2,256 ) . for all causes , rejections among male young persons numbered 468 , and among female young persons 1,008 , an increase of 19 and a decrease of 89 respectively over the previous year &apos;s figures . chapter 2 . review of the year . this record of some of the more prominent features of the year &apos;s activities and developments in the field of safety , health and welfare is presented in four sections . the first records some of the more important industrial developments affecting the safety , health and welfare of factory workers which come to the notice of H.M inspectorate of factories during 1960 . this is followed by a brief reference to the activities of international , industrial and voluntary organisations in this field . a section on fire refers to the arrangements made to implement the new provisions of the factories act , 1959 . the chapter concludes with a summary of relevant legislation passed during the year . 1 . industrial developments . a . electrical developments . electricity supply - general developments . the demand for electricity continues to double every 10 years . such a rate of growth demands the addition of large quantities of new plant annually and , in order to save expense and space , a great increase in the size of individual units : generating sets of up to 550 MW and transmission systems to operate at 500 KV are now being designed . the speed of technical progress leaves designers with less opportunity to modify designs on the basis of working experience ; the more exacting planning requirements are being met by the increased use of computers and other aids . automatic torque angle control has been introduced on the new large generators , whose safe operation at the extreme limit of stability would be beyond the capacity of the human operator . difficult problems of protection under fault conditions have also to be tackled by area and distribution engineers as a result of the heavy concentration of power at sub-stations . problems involved in the operation of steam turbo-generators . in order to provide continuity of electricity supply from large turbo-generators running in parallel , designers and operating engineers must understand both the balance between steam utilisation and electrical output and the influence of the connected electrical system upon the running speed and operational stability of the generator . on several occasions this balance has been seriously disturbed , e.g , by the failure of the turbine governor gear immediately to reduce steam supply to compensate for a sudden loss in electrical load . consequently speed has risen rapidly beyond the designed maximum , even with a centrifugal governor operating the steam through an oil hydraulic system and backed by an emergency governor . centrifugal forces are capable of causing the turbine to disintegrate with serious damage to buildings and even loss of life . research and development have been undertaken to reduce these hazards , which can be expected to become more serious as turbo-generators increase in power . modern turbines are provided with anticipatory gear to detect and to correct instantly any violent rise in speed as with means of testing and checking the freedom of movement of the governor mechanism without taking the machine off load . in the unit system , where boiler , turbine and ancillary plant are integrated , controls are located in a single operations room under the supervision of a co-ordinated team . instruments , controls and alarms are so grouped that quick reference can be made to both steam and electrical conditions . wherever possible the principles of failure-to-safety or back-up protection have been incorporated in the design . developments in electronic engineering . some of the more outstanding recent advances have been in the field of semi-conductor engineering . the advantages of semi-conductors are absence of moving parts , an indefinitely long life without maintenance and extreme versatility of function - including measurement , amplification , instrumentation , control , rectification , inversion and switching . generally these devices tend to promote safety by their innate characteristics and reliability ; they also enable many new safety devices to be designed ; electromagnetic relays with mercury-wetted contacts are now available with a life-expectancy of hundreds of millions of contact operations and at the same time the robustness and reliability of electronic valves have been greatly improved . progress in miniaturisation , also partly dependent upon semi-conductor techniques , can be expected to contribute to industrial safety in due course and eventually to make possible the construction of self-adjusting - monitoring - correcting and maintaining mechanisms of unprecedented reliability . the use of electricity on constructional sites . in 1960 approximately one-eighth of all electrical accidents , including one-third of the fatalities , occurred on building and constructional engineering sites covered by the factories acts . the largest group of these was caused by portable electrical apparatus and its associated flexible cables and accessories , the next largest group was caused by other types of wiring . interesting developments are taking place on some of these sites with a view to reducing the risk of electrical accident , e.g : - ( 1 ) . in the construction of multi-storey buildings , rising mains at 415/240-V are installed in the form of cable so situated as to be protected against casual damage and 240-V single-phase supplies are tapped successively on to the various floors . this is economical and ensures that not more than one phase is available on any one floor during the work . local voltage reduction by single-phase transformers on each floor is then installed for the period of the job . ( 2 ) . an alternative arrangement is to follow up the building work from floor to floor with a supply of carcase wiring sufficient for the operations , thus reducing to a minimum the amount of flexible and temporary wiring . voltage reduction is then used on each floor . ( 3 ) . with transportable machines which are too large for single phase-motor drives , the practice of using three-phase motors with voltage reduction is growing . a transformer with a secondary output at 110-V , three-phase with earthed neutral point gives a voltage to earth of approximately 64-V , a value likely to be safe in all but the most exceptional circumstances . ( 4 ) . a common system of festoon wiring found in use in lighting the work required the piercing of cable by sharp contacts at points where it was necessary to instal lampholders . the risks of shock from leakage and pierced insulation made this wiring unsuitable for construction work . it is a most welcome development that makers are now producing an improved form with the lampholders moulded to the cable at such intervals as the purchaser may require . prevention of accidents at overhead electric lines . the problem of accidents from contact with overhead lines remains serious ; 107 such accidents have occurred in factories since 1954 , of which 44 have been fatal . while there has been some improvement in accidents from contact by cranes or similar machines the number caused by direct contact with lines - 20 , including six fatal ones in 1960 - has reached a level that gives cause for concern . attempts are being made to develop equipment to fix on the crane which might reduce the risk of shock from contact with the line . the equipment takes two forms - an insulating guard on the jib of the crane , intended to prevent direct contact with the line , and electronic equipment with a sensitive probe mounted slightly forward of the head of the jib and with electronic assembly and warning apparatus in the driver &apos;s cab . improved designs of both forms are being tried out at present . there is , however , a danger that workers will rely too much on fixed devices because they fail to recognise their limitations . it is therefore safer both in principle and practice to keep the worker away from overhead lines wherever possible , e.g , by ( 1 ) re-routing the line , ( 2 ) putting the supply underground , ( 3 ) making the line dead ( after consultation with the supply authority ) , ( 4 ) providing barriers at a safe distance to prevent vehicles from approaching the line , or height gauges or goal posts at points where vehicles must pass below the line , ( 5 ) providing look-out men or banksmen . it is also important to remember that on lines carrying the higher voltages flashover from the line may take place without actual contact . b . engineering developments . leather industry - leather rolls . a new type of machine has recently been developed for the automatic rolling of sole leather bends . the sheet of leather is placed on a sliding feed tray outside the danger zone and is then pushed forward between two platens , the upper one carrying a set of small rollers . the lower platen , which supports the leather , is raised hydraulically to bring it into contact with the rollers on the upper platen , which is then caused to make several horizontal oscillations so that the leather is rolled and pressed at the same time . the danger zone between the platens is fenced by a guard which is interlocked with the hydraulic valve and the press is also sequentially operated : the closing of the shutter starts the machine , the rest of the cycle following automatically . brickmaking machinery - new sanding method . a new method of applying sand to the faces of green bricks has recently been developed . in the case of wire-cut bricks the column of clay from the pug-mill is carried by a short length of belt conveyor to the sanding plant . this consists basically of a vibrating hopper from which the sand is distributed to all four faces by a system of slots , scrapers and worms . the conveyor is broken at this point to enable the sand to be applied to the under surface of the column , which passes on through two pairs of vibrating rollers which embed the sand firmly in the surfaces and is finally cut into bricks at the wire cutting table . 