METHODS OF KAT DESTRUCTION. 241 



cord controlling the door. This contrivance having proved .a 

 success we were anxious to give it a trial. The weak part, how- 

 ever, of this trap appeared to be the amount of time that would 

 be wasted by the man controlling the sliding-door, and therefore, 

 in order to dispense with the human element, with the help of 

 my friend Mr. Mark Barr, I worked out a scheme which enabled 

 the open door, which i*ested on a hinge, to fall l)y being drawn 

 towards an electro-magnet, the latter being in contact with a 

 number of batteries and an alarm-clock. Thus if we wished the 

 <loor of the trajo to be shut at a certain time all that was 

 necessary was to set the alarm for that time, when the current 

 acting on the magnet released the door. .With this a number of 

 rats were captured. During the winter months, when less food 

 is available, it may jjossibly give still better results. 



The steel Gin trap has for years been used with success, and is 

 the type generally popular with the gamekeeper. Nine hundred 

 and seventy-three of these traps laid down in our Gardens were 

 during the four months in question responsible for 173 I'ats, a 

 percentage of 17. Considering that we obtained a, higher per- 

 centage with the Brailsford trap, we presumed that the gins 

 would be specially successful if laid in the centre of any passage 

 showing light at the far end, and we consequently experimented 

 by covering them with large drain-pipes cut longitudinally in 

 half. This experiment was, however, a failure. At a later date 

 we continued the experiment on the same lines and had holes 

 bored in the top of the pipes in order to allow for some light to 

 enter. This was slightly more successful than when the niiddle 

 of the pipe was in complete darkness, and a feu' i-ats were 

 caught. The results, however, could not compare with those 

 obtained when the traps were put down in the usual manner. 

 As the Brailsford traps continued to give such satisfaction, I 

 ordered a number of covers exactly similar to those of the cage- 

 trap, but without doors, bottom or centre platform, in order to 

 ascertain whether, when the gin-traps were covered with these 

 wire -passages, a higher percentage of successes would be attained. 

 The result was highl}' satisfactory, the gins, when placed under 

 these cheap Avire-covers catching almost as many i-ats per trap as 

 the Brailsford and a higher number than when placed in runs 

 in the ordinary way. 



Break-hack traps. — With one exception these gave no good 

 results. The exception was a type known as the " Nipper," and 

 with 1962 of these traps 237 rats were caught. This, a very 

 inexpensive trap, is most suitable for putting down indoors or 

 under tover, as in wet weather the wood is liable to warp and 

 render the appliance useless. We would suggest to the makers 

 that a similar trap be made of metal for outdoor use. As in the 

 case of the Gin traps, the " Nippers," when placed under wire- 

 covers, were i-esponsible for a higher percentage of captures. 

 The figures below show results obtained with 100 Gin and 

 100 Nipper traps when laid down in the ordinary manner and 



