SLIPS ON THE ILLAWARRA RAILWAY AT STAN WELL PARK. 61 



the centre of the embankment and finished with a dead end, and 

 the other two were carried only to the foot of the embankment. 



The effect of these drains was very marked, at the commence- 

 ment of the work the ground was so soft that there was consider- 

 able risk of getting bogged when attempting to walk upon it, and 

 it was found that when the first set of timbers were being fixed, 

 that the ground was slipping past at the rate of fully four inches 

 per day, but as the cuts advanced this motion gradually ceased, 

 and the ground near the drains became hard and the fissures 

 gradually closed up. Large quantities of water were struck as the 

 cuts advanced, but it soon ran out of the ground and at the time 

 of the completion of the works there was only a very small stream 

 running from each of the pipes over the cliff, and by the end of 

 1889 a good crop of couch grass had grown over the work and 

 nothing could be seen to indicate that any extensive works had been 

 carried out. All the timber except that in the drives was drawn. 



The author little thought that the efficiency of these drains 

 would have been so soon put to so serious a test as has been the 

 case since the beginning of the present year. In Sydney the rainfall 

 from the 1st of January to 9th May amounted to 48 556 inches, 

 and at Stanwell Park although no record has been taken, there is 

 every reason to believe that this large amount has been exceeded. 

 It is satisfactory to note that not the slightest movement has taken 

 place in this embankment, although in many places that stood the 

 great storm of May 1889 serious slips have taken place, the only 

 damage done at the 33 mile bank was that a very slight slip has 

 taken place between No. 5 and 6 drives at the edge of the cliff, 

 but not sufficient to in any way endanger the stability of the line. 



In connection with the carrying out of these works the author 

 was very fortunate in having the services of a very experienced 

 miner, Thomas Smith, and it is is very gratifying to record that 

 not the slightest mishap occurred during the carrying out of this 

 difficult work. Several serious slips have taken place in the town- 

 ship of Clifton during the recent rains, and these the author is 

 treating in a somewhat similar way to that successfully carried 

 out at the 33 mile bank. 



In conclusion the author would remark that the treatment of 

 slips is by no means an easy problem as every case has to be care- 

 fully studied, thus in many descriptions of clays, burning has been 

 found a most effectual cure, in other places retaining walls have 

 succeeded, and many other systems have been carried out with 

 more or less success, but in every case it is absolutely necessary 

 for the engineer to make himself familiar with the nature of the 

 soil before starting work unless he wishes to be disappointed with 

 the result. It has been said by some people that slips are things 

 that should have been foreseen and guarded against by the 



