I am an electromagnet of 100 horse-power, and permanent soft iron keeper of 60. I was

I am an electromagnet of 100 horse-power, and permanent soft iron keeper of 60. I was first soft iron alone, but permanent steel was added to me, and permanent soft iron to the keeper. Together, we have a power of 160 horses. I was first keeper of a small soft iron horseshoe, but now I have a keeper of 60 horses' power. I was first keeper of 20, but now of 160. I have soft iron keepers of 60, 80, and 100, but permanent steel of only 60. I have keepers of 160, but of no more than 160. I have keepers of 160, but of no more than 160. I have keepers of 160, but of no more than