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of Brightside Works, Park Works and Soho Works, Sheffield
1774 Company established.
1830 Company took the name William Jessop and Sons
1875 The company was registered on 14 December, to take over the business of the firm of this name as ironmasters, smelters, engineers, ironfounders and manufacturers. 
1876 Announce they are concentrating all their workman at the Brightside Works. 
1885 Gold medal for invention for crucible cast steel stern frames, solid rudder, and cast steel stern propeller brackets and blades.
1887 'Among other exhibitors at Manchester are Messrs. Wm. Jessop and Sons (Limited), Brightside Steel Works, who have sent a large steel spur rim casting. It weighed 14 tons,and was 18 feet in diameter. It was too large to go by rail, and had to be sent by road, and its progress was rather noteworthy, as recorded in another column. Messrs Jessop aad Son have a special reputation for this class of work. They recently made several wheels about the same size for Messrs. Schneider, Creusot, France, where they will used in their large new steel plate-mills. ...' 
1894 Improvements to their works. 
1894 New type of Siemens-Martin furnace. 
1914 Steel manufacturers. Specialities: high-grade crucible steel for every purpose, producers of steel forgings and steel castings in the rough or finished state up to sixty tons weight for marine, railway, mining, electrical and general engineering and for motor vehicle construction. Employees 2,000. 
1920 Acquired by the Birmingham Small Arms Company. (BSA)
1927 See Aberconway for information on the company and its history.
1937 Steel manufacturers. "Ark" and "B4 Any" Steels. 
The full newpaper report is transcribed here, as it offers some insight into the dangers, the methods, and the inquest process.
'THE FATAL ACCIDENT AT MESSRS. JESSOPS'.
INQUEST THIS AFTERNOON.
This afternoon, at the Infirmary, Mr. D. Wightman resumed the inquiry, into the circumstances attending the death of Henry William Booker, a moulder, who died from the effects of injuries received in the explosion which occurred on May 30, at Messrs. Thomas Jessop and Sons' works, Brightside. The inquiry was opened a week ago and adjourned for the attendance of Mr. Banham, the manager, and a workman named King, who were injured by the explosion and were not well enough to give evidence last week. Mr. Banham attended to-day, but it was stated that King was still very seriously ill, and not fit to be present.
At the commencement of the inquiry the Coroner said he was glad to see that Mr. Banham was sufficiently well to be present and give evidence, as he was a man in authority at the works.
James Banham, steel manager, of the crucible steel department at Messrs. William Jessop and Sons (Limited), said the deceased worked under his orders. On the 30th May, about five o'clock, the deceased and others were assisting to cast an ingot weighing about 60 cwt. The steel was run into a bucket in the ordinary way. The bucket was placed over the pit. He was standing near, and the deceased was on the opposite side. He (witness) told Joseph King to draw the plug steadily for the purpose of letting the molten steel into the mould. King did it steadily. The steel began to boil in the bucket, and then he knew something was wrong. Immediately afterwards the explosion occurred and blew most the steel out the bucket. He, King, Gregory, and two others were slightly burned.
The Coroner Now comes the question. You were the man in authority, were not? —Yes.
Now how do you account for this? It doesn’t blow up every day does it? —Certainly not.
Now what was the cause?— Damp plug.
Have you any doubt about that?—No, sir.
Who had the management responsibility this plug? -King:
How is he? Can he give evidence?—No, sir.
Did you see the plug before it was put in, then? — Yes.
Did you handle it?— No.
Did you examine it at all?— No.
Wasn't it part of your duty to so?— No.
But if you were authority whose duty was it? King's.
Tell me the process which is gone through for the purpose of making this plug fit do its work? What is done at it?— Lined up with composition.
What kind composition?— Ground gannister, &c.
How had he to dry it?—in the melting furnaces.
Any more than one plug, do you use the same plug all along ?—No, there are several plugs. We were using two plugs at the time. King has had the control of these plugs seven eight years.
Has anything of this kind ever happened before? No, sir.
From the dampness of the plug has it ever partially exploded before?—it has often boiled from the dampness in the bucket.
How can that get damp?—By lining the same as a plug.
You line it at the same as plug?— Yes.
The same stuff ?—Yes. The bucket was lined each time for casting with the same material as the plug. He thought that the explosion must have arisen from the dampness of the plug, as it was the plug that exploded. The plug had not been used since the previous day. The inside the plug must have been wet. He considered that half a pint of water at the bottom of the bucket, if confined in one place, would be sufficient to cause the explosion. The damp must have been confined in the centre of the plug. At this point the remains of the damaged plug and also a perfect one were produced and examined.
Mr. Banham, continuing, said he did not think it his duty to examine the plug before every casting. This was left to King. The plug was hollow.
The Coroner : Had the same means of drying this plug that he has had for all these years?—No, sir.
Well then how was it? —He has been on different parts of the works doing this sort of thing. He will have been doing this kind of thing in the same place for several works.
How you account for his not getting that plug dry as he generally got it before?—l don't know, sir, unless he made it up wetter, and did not give it sufficient time.
Had he the same means of drying it?— Yes.
The same means?— Yes.
The same place?— Yes.
And the same time allowed him?— Yes. He has been managing these plugs seven or eight years.
Is he a man who drinks at all, King?—No, sir.
Is he a steady man?— Very steady.
You have no reason to think it has arisen through his not being quite sober?—No, sir. I believe he is a teetotaller.
You have reason to believe it arose through any neglect on his put and having too much to do?— No.
Had he sufficient time to it?— Yes; he only had two do that day.
Juryman : you have reason to believe ho took the ordinary course?—Yes.
And nothing else? Yes.
The Coroner: Did he case them as you had seen him do them numerous times in a proper manner? —Yes.
Is it your opinion that this accident has arisen entirely and solely through the plug not being sufficiently dry? -Yes.
And nothing else?— Yes.
The Coroner, addressing the jury, said he did not think it necessary to call any further evidence, but it was for the jury to decide. The only question appeared to be what was the amount of blame, if any, attaching to King. When adjourned the inquest he had some doubt whether it was not Mr. Banham's duty to see the plug was properly dry. Mr. Banhain hid explained that King had done the work for a number of years, and that he considered him a competent person. King had done this so long that in all probability he (King) considered that on that occasion he had dove it in the ordinary way. He did not think they could come to any other conclusion than that King had considered the plug to be safe.
A Juryman said he should like to have some evidence about the drying of the plug.
Walter Liversedge, puller-out, deposed to seeing the plug at the back of one of the furnaces when he went to work at six o'clock in the morning.
Luke Ogden, odd man, stated when he went to work in the morning he saw two plugs standing at the back of the furnace. He moved the plugs a short distance from the furnace as they were in his way.
The Coroner: Now we seem to be getting at the real explanation.
Witness, continuing, said that he had moved plugs on several previous occasions. He did not examine the plugs when he moved them see whether they were properly done or not. They had been there all the night.
The Coroner asked whether they would adjourn the inquest for the attendance of King. If he thought King would do any good he would have adjourned without consulting them. He did not see what good King would do them. He had no doubt King would tell them be thought the plugs were dry, and that he put the composition on the way he had done it in previous years. He was not likely to throw any blame upon himself.
The jury did not desire to adjourn.
The Coroner thought they had thoroughly bottomed the matter. The last witness had innocently enough doubt contributed to the accident by removing the plugs from the place where they were drying to a place where they would not dry. If he had been able to leave them alone till King wanted them, in all human probability the accident would not have happened. The jury returned a verdict of "Accidental death," the Coroner suggesting that in future the plugs should provided with a proper place for drying, a place where they would not in the way of anyone. The proceedings then terminated.