To IWIAS homepage

Rockets can be traced back to China around 1000 AD. By the 13th century they had found their way into Europe. This illustration shows them in use during the Napoleonic Wars

One of the most unlikely phrases to be used by Islanders in describing where they live has to be At the forefront of Rocket Science. All the same there have been many occasions over the last couple of centuries when it certainly would have been a very appropriate description.

A visit to High Down confirms the work done by Saunders-Roe on the Black Arrow and Black Knight rockets during the 1950/60s. Some residents may well remember seeing, or even working on, the rocket assisted planes of the same era, while those of an earlier generation may still recall the attempt by the German, Gerhard Zucker, in 1934 to fire a liquid-fuelled rocket with a payload of post from Lymington Marshes to the Yarmouth area. From about 1865 until after the Second World War, Boxer rockets were used for firing rescue lines to ships in distress. Although these were always made at Woolwich, Edward Mourier Boxer lived at Upton House, Ryde, until his death in January 1898.

John Dennett

On the Isle of Wight, well by the time of the Reform Act in 1832, John Dennett, had already designed, built, tested and had patents on his life-saving rocket apparatus and other rocket and mortar designs. It is to John Dennett, his son Horatio and their rockets that this report is dedicated.

Dennett's Origins

Little seems to be known about the life of John Dennett except that he belonged to a well-established Island family based at Carisbrooke. Today descendents, living on the mainland, have in their possession what they think could well be a box made by a Dennett of Carisbrooke to hold a communion set for Charles I, who had left the Castle before it could be delivered (i). What influenced John Dennett, born 25th September 1780, to develop a lifelong fascination with rockets and mortars is a mystery. However, he himself wrote in a pamphlet printed in 1832 (ii) "...A natural fondness for pursuits connected with Naval and Military Mechanics, has led me to devote a large portion of time and expense, in experiments on those favourite subjects; from which, amongst many other inventions, the production of these rockets has been the result ..." It is thought likely that during the Napoleonic Wars John Dennett was manufacturing military rockets. Still for him a great concern at the time must have been the heavy loss of life through shipwreck on lee-coasts of the British Isles, and this no doubt provided much of the stimulation for his development of the humanitarian uses of the rockets. In a patent application (iii) he describes himself "... I John Dennett, of New Village, in the Isle of Wight, in the County of Hants, Engineer and Surveyor ..."

Development of the Life-Saving Rocket

 Rescuers using a rocket to fire a line over a ship in distress. A strong line is then hauled to the ship which can be used to either guide a rescue boat or establish tackle to bring ashore individuals

By 1807 George Manby, barrack-master at Yarmouth, Norfolk, had demonstrated his mortar for use in sea rescues, and by 1817 Henry Trengrouse had published a pamphlet on his use of rockets for 'saying lives in the case of shipwreck'. A copy of which he claimed had been deposited in the circulating library for sailors at Cowes before 1824. It is not known whether it was seen by John Dennett or not.

In January 1826 there was a Report of Captain Clavell, RN, commanding His Majesty's Ship Prince, and twelve other Naval and Military Officers, on experiments made with Rockets.
   "We, whose names are subscribed, do herby certify, that we have been present at experiments made with Mr John Dennett's Rockets; and we are fully of the opinion that they will answer every intended purpose in case of shipwreck. Those of twelve pounds weight, will convey a large line against the utmost power of the wind, more than three hundred yards; a distance much greater than shipwrecks generally happen in any part of the coast of England. And their small weight in transporting from place to place, amongst the cliffs, and their peculiar efficacy in a dark night, renders them far preferable to any apparatus we have ever seen for that purpose".
Their report led to the establishment of three rocket stations here on the Southern Coast of the Isle of Wight at Freshwater, Atherfield and St Lawrence. A year later Thomas Robert Brigstocke, of Ryde and the Inspecting Commander of Coast Guard Isle of Wight, also reported favourably on the use of the rocket to the Secretary of the Royal National Institution for the Preservation of Life from Shipwreck.

Thus the scene was set for the real breakthrough in 1832, when a Dennett rocket, from the established station at Atherfield on the Island, rescued some 19 survivors from the wreck of the 400ton Bainbridge with a full cargo of rum and deals. It got national coverage and resulted in a contract of £300 a year for the rocket's use by coastguards. John Dennett quotes several testimonials later in one of his own pamphlets publicising his rockets, including this one from the captain and mate.(ii)
   "We hereby certify that the Bainbridge, from Halifax for London, was wrecked during the heavy gale, on the night of the 7th -8th inst, on Atherfield Rocks, at the back of the isle of Wight; that four attempts were made with Captain Manby's apparatus to throw a line over the ship, without success, owing principally to the great distance she lay from shore. A Rocket of Mr Dennett's invention was then fired, and at once carried the line to its destination in the most complete manner, although the position of the ship was most unfavourable for such a manoeuvre, as she lay end on, with her stern towards the shore. The communication thus established, a strong rope was hauled onboard, and a boat drawn through the surf, by which the crew, nineteen in number, were in two trips safely landed upon the beach. The superiority of the rocket was most evident to all, and the proof is in the result. That they come into general operation upon similar occasions, we heartily wish, and we give our most hearty thanks, (as is most due,) to Mr Dennett, for his exertions in the cause of humanity."
William Miller, Master
Joseph Irwin, Mate
Atherfield, Oct 10, 1832

In 1833 The Hampshire Telegraph reported "On Monday last (26th August) Princess Victoria and the Duchess of Kent went to the Earl of Yarborough's, St Lawrence Cottage. The Royal Party went by yacht and anchored in Mill Bay. A temporary jetty was erected for them to land from their barge. They saw a demonstration of Mr Dennett's Rockets, for preserving lives from shipwreck, as requested by the Duchess of Kent." (vi)

For much of 1835, training and comparison exercises between mortar and rocket were taking place around the country in places such as Tynemouth, Blyth and Yarmouth. Gordon Harris, who owned and ran a ropery at Hull, sponsored extensive tests in the first week of September on the beech at Skegness. After analysing the Skegness results, George Manby concluded that the future must be in rockets and invited Dennett to be a guest and stay with him at his home in Yarmouth. (vii)

1838 saw another of John Dennett's patents showing his continued interest in the development of rockets, and even mortars, for a variety of purposes. His inventions this time consisted of "Improvements in war Rockets and in the Method and Apparatus for applying the Powers of Rockets for the Purpose of Obtaining Communication with Vessels which are Stranded, or in any other Situation of Danger; Also, an Improved Instrument and Method for Accurately Pointing Mortars for Throwing Shells, which may likewise be used for Firing Shot from Mortars, for the Purpose of Obtaining Communication with Ships." (viii)

Trials and comparisons were to continue for many years and by the time of the 1843 Shipwreck Committee hearings, Dennett's rockets had been instrumental in effecting rescues all around the British coast. Many of the coastguard stations kept both Dennett's rockets and Manby's mortar, some preferring one to the other. 120 stations held rockets by 1853. Colonel Boxer's device, consisting of placing two rockets in one tube, one behind the other, was developed by 1865. However the Dennett rocket continued to be used for many years to come, but for how long is not clear. As late as January 1890 there was the thrilling rescue of 36 crew of the three-masted ship "Irex", driven ashore in Scratchells Bay, when all were hauled one by one to the top of the 400 foot cliff with the help of Dennett's apparatus.

A later Boxer Life-Saving Rocket (Carisbrooke Castle Museum).
It was similar in appearance to a Dennett but with a slightly smaller diameter head

The Dennett Rocket Apparatus

Dennett's apparatus resembled a sky-rocket but instead of the paper case of the sky-rocket it had an iron case and a pole rather than a 'mere stick'. Weights varied, but typically one of 23lb including 9lb of solid fuel would have a range of 250 yds. (v)

In comparing the mortar with his rocket, Dennett in his writings and pamphlets stressed the saving in time not only in transportation but in preparation and that his rockets were less likely to get wetted by rain or spray. He also pointed out that they "could be transported with great ease and expedition by two men, from a Station to a distant wreck, whilst the Mortar and its necessary stores, cannot, from their weight, be removed to a distance wreck along the cliffs or a rugged beach, without great difficulty and loss of time." For the same calibre the rockets have a much longer range in all weathers. He also pointed out that only one line is required for repeated shots and another advantage was at night he pointed out the rocket course can be seen. Finally he compares the total weight of equipment:

Mandy Mortar - exclusive of grapnels, hand-barrow
cwt qu lbs
Weight of five and a half inch Brass Mortar 1 1 10
Bed (various) about 1 2 0
6 shots of 24 lbs 1 1 4
6 cartridges at 8ozs, Priming tubes etc 0 0 5
6 lines at 28lbs each 1 2 0
Total 5 3 1
Dennett Rocket
cwt qu lbs
6 Rockets at 9lbs 0 2 0
2 Cartouches 0 0 6
Rocket Frame 0 0 20
6 Poles and Portfire Staff 0 0 15
Line 0 1 0
Priming Tubes, Portfires, 0 0 4
Total 1 0 17


When John Dennett died 10 July 1852, Horatio was left with the family business. Slowly after 1865 the Boxer rocket, also with its Island connections, was to replace the Dennett. We can see this decline from the local trade directories: in 1859 Horatio describes himself as ‘a rocket manufacturer’, in 1875 it is as ‘a civil engineer’ and by 1878 ‘brick manufacturer, Carisbrooke’. But by the census of 1881 Horatio Dennett, of 89 Clatterford Road, is back to describing himself as ‘a retired manufacturer of Dennett rockets’. He was to die the end of November 1897 and was buried beside his father.

Little appears to be left to remind us of the era of the Dennett rockets. Even the Museum at Carisbrooke Castle, where John Dennett was the castle custodian for some years, only has a later Boxer record in it's collection. The Coastguard Museum in Yorkshire has a spare-part tin for a rocket amongst its collection! In the maritime collection of Cowes Library are several items including 'Instructions for using Dennett's Rocket', Description of Dennett's Rockets for Preserving Lives from Shipwreck', plus photocopies of a number of other items. The Dennett family tomb is situated at the east end of the churchyard of St Mary's at Carisbrooke. However, David Haskoll, living now in Surrey, whose ancestor married into the family, has a few letters (i). One of 1836 mentions that a letter from George Manby had been received which acknowledging the superiority of the rocket over his mortar. It also refers to John's application for patents. Just what buildings the Dennetts had, and where they were situated in the Gunville Lane area, supporting the manufacture of the rockets is not known. Filling sheds and other buildings used for explosives have to be flimsy in structure and are usually widely scattered. No records have been found of any explosions or accidents!

Work is still going on in trying to trace more information on the Dennetts through records of military and other regulatory authorities of the time controlling the manufacture of explosives in Britain.

(i) Private collection David Haskoll
(ii) Description of Dennett's Rockets for Preserving lives from Shipwreck
(iii) John Dennett Patent 1838 No 7759
(iv) The Mariner's Mirror, 1997 Nov Vol 83 No 4 p434, W.B.C. Prober
(v) Chamber Encyclopedia 1874
(vi) Hampshire Telegraph 1833 Sept 2
(vii) From Rock and Tempest, Kenneth Walhew 1971

Patrick A. Nott