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1843 February 1st. Born in Rome the son of Thomas Thornycroft (1815-1885) and his wife Mary Francis. Both parents were sculptors and were studying at the Vatican when he was born.
1851 Living with his uncle William, a farmer, and his wife, Alice, in Gawsworth, Cheshire
His father, recognizing his interest in designing and building boats, decided formal training would be appropriate.
1860 He built his first steam launch - the 36ft 'Nautilus' - when he was 17 years old, in the studio of his father, who, at the time, was engaged on the Boadicea group of statues which was placed at the corner of Westminster Bridge.
John worked at Palmer’s Shipbuilding Company, Jarrow-on-Tyne where he gained some practical experience.
Then went to Glasgow University, the only place where naval engineering was taught. He obtained his diploma in engineering under the instruction of Lord Kelvin and Professor MacQuorn Rankine.
1864 He started shipbuilding on the River Thames at Chiswick.
Educated at the Royal School of Naval Architecture and Marine Engineering at South Kensington (query when this happened if, as said in the obituary below, he was a contemporary of Sir Philip Watts, then he would have been at the school in 1866 or later)
1866 Established his shipbuilding business John I. Thornycroft at Chiswick.
1870 October 8th. Married at Camden to Blanche Ada Coules, the daughter of John Frederick Coules, Tanner and Bark Merchant
1877 His first vessel for the Royal Navy was a motor torpedo boat.
His yard built a steam powered lorry which led them into the vehicle manufacturing business, the Thornycroft named business lasting until the late 20th century.
Thornycroft worked on means of aiding hull lubrication by air which also led him to hydrofoil. This led him to develop stepped chine hulls which used for 55 ft Coastal Motor Boats during the war gave them speeds of up to 40 knots.
1891 Living at Steyne House, Brading, Hants (age 48 born Rome), a Civil Engineer and Employer. With his wife Blanche A. (age 45 born Gloucester) and their children Edith A. (age 19 born London), Blanche C. (age 17 born London), Mary B. (age 15 born London), Ada F. (age 13 born London), Eldred E. A. (age 12 born London) and Isaac T. (age 9 born London). Also a visitor from Brazil and five servants. 
1904 THORNYCROFT, Sir John I. The name of Thornycroft holds a pre-eminent position in the heavy motor vehicle industry, but it will he a surprise to many people, even motorists of long standing, to know that the head of the great steam wagon company of Chiswick and Basingstoke designed an automobile as far back as 1860. It is a fact nevertheless, but pressure of work in connection with his very successful inventions in torpedo boat construction necessitated Mr. Thornycroft withdrawing his attention from this subject for many years. The revival of interest in automobilism, however, in 1896 caused him to again direct his attention to the subject, and experimental works were instituted by him at Homefield, Chiswick; later he laid down a large and well-equipped factory at Basingstoke, where for some years past the manufacture of heavy-load steam vehicles, and steam passenger cars, has been undertaken. Very great success as everybody knows, has attended the venture so far, and the Thornycroft wagons are now well known and appreciated all over the world. The honour of knighthood was conferred upon Mr. Thornycroft in 1902. He is a Fellow of the Royal Society, a Doctor of Laws, and a Member of Council of the Inst. Civil Engineers. Sir John, is, with his sons, now engaged in building petrol cars, and it is needless to say that these will be of very first-rate design and construction they will he wholly made by the Thornycroft Company. The military motors that Sir John I. Thornycroft's firm have manufactured have been greatly praised by the Pall Mall authorities, who, in the War Department trials of 1901, awarded these vehicles the first prize. 
1904 he transferred the larger shipbuilding activities to Southampton.
1908 he set up the Hampton Launch Works on Platts Eyot, an island on the Thames at Hampton, Middlesex.
1909 Biographical information and image at Automotor Journal 1909/08/21
1911 Living at Eyot Villa, The Mall, Chiswick: John Isaac Thornycroft (age 68 born Holy Rome), Marine Engineer (Retired). With his wife Blanche Ada Thornycroft (age 64 born Gloucester) and three of their children; Edith Couish (age 39 born Hammersmith), a widow; Blanche Coules Thornycroft (age 37 born Hammersmith); and Eldred E. A. Thornycroft (age 32 born Chiswick. Also his mother-in-law Elizabeth Coyles (age 94 born Hants). Six servants. They have been married 41 years and have seven children.
This boat-building works concentrated on cabin cruisers and speedboats, but also produced small naval craft - Coastal Motor Boats in the First World War and Motor Torpedo Boats, Motor Launches and landing craft in the Second World War. Thornycrofts closed their boat-building operation on Platt's Eyot when they were taken over by Vospers in the mid-1960s.
The Southampton shipyard continues to operate as a VT Shipbuilding (Vosper-Thornycroft) company.
Sir John Thornycroft was the brother of Hamo Thornycroft, the British sculptor, and uncle of the war poet Siegfried Sassoon. His son Isaac Thomas Thornycroft skippered the motorboat Gyrinus II to two gold medals at 1908 Olympic Games.
1928 Obituary 
Sir JOHN ISAAC THORNYCROFT, LL.D., was born in Rome in 1843, where his parents, who were both sculptors, were studying works of art. Thomas Thornycroft was the designer of the Boadicea group on the Victoria Embankment, but besides being an artist of distinction was a keen mechanic, and it was in his workshop that John Thornycroft found his talent.
He studied under Lord Kelvin (then Sir William Thomson) and Professor MacQuorn Rankine at Glasgow University, and worked for some time in Elder's drawing office at Fairfield.
He had already built several model steamboats of quite remarkable character, and in 1866 he founded the firm bearing his name, and established works on land given to him by his father at Chiswick. Here he built the "Miranda" and the "Gitana," steam-launches with compound engines and locomotive-type boilers that successively set up new standards of speed, 18.625 and 24 m.p.h. respectively. Shortly afterwards the first torpedo-boat ordered by the British Government was built—the "Lightning."
The special character of the firm's productions and the foundation of the long series of naval constructions, culminating in the latest Thornycroft destroyers with a speed of over 40 knots, were thus definitely established. The construction of water-tube boilers was presently taken up, and the first warship to be so equipped was the torpedo gunboat "Speedy."
The removal of the works to Woolston, Southampton, was necessitated by the increased size of the vessels built and repaired by the Thornycroft works. About the same time the naval committee appointed by Lord Fisher, of which Sir John was a member, decided upon the turbine in preference to reciprocating machinery for warships, so that the opportunity was taken of equipping the new works with plant suitable for turbine construction.
It was while at Chiswick that Sir John first turned his attention to the construction of self-propelled road vehicles. His first carriages were steam-driven, but eventually the construction of the Thornycroft internal-combustion engine driven vehicles, now carried on in separate works at Basingstoke, was commenced.
Sir John himself took out between fifty and sixty patents during the half-century between 1873 and 1924, and was associated with very many more. The greater number of these refer to his marine work, but so prolific was his inventive genius that they include patents in connexion with the extraction of beet sugar, the prevention of injuries to stokers from burst boiler tubes, means for driving models in experimental tanks, a method of making observations from aircraft, and door fastenings.
Sir John built an experimental tank at his home on the Isle of Wight from which many of his most important improvements in hull forms originated, and which, in particular, was of the greatest value in the evolution of the coastal motor boats built by his firm during the War.
He became a Member of the Institution in 1876, and was a Member of Council from 1897 to 1911.
In 1926, on the fiftieth anniversary of his becoming a Member, he was elected an Honorary Life Member in view of his eminent scientific attainments. He was also a Fellow of the Royal Society and a Member of the Institutions of Civil Engineers and Naval Architects.
His death occurred on 28th June 1928, in his eighty-sixth year.
1903 Bio Note 
THORNYCROFT, SIR JOHN I., F.R.S.- Born at Rome in 1843, was educated at Glasgow University. Sir John I. Thornycroft is the founder of the shipbuilding works (1866) at Chiswick bearing his name. He is Vice-president of the Institute of Naval Architecture, a member of the Council of the Institute of Mechanical Engineers, also of the Institute of Civil Engineers. His principal pursuits and recreations are small boat sailing, racing, skating, photography and cycling. Sir John I. Thornycroft has been a member of the Club since August 9th, 1898, and has served on the Club Committee since that date also on the Richmond Show Committee of 1899. Municipal and other horseless vehicles for heavy goods transport have so far been the leading manufactures of his firm in automobiles, but at the last Crystal Palace Exhibition for the first time a passenger car made by his firm was on show.
1929 Obituary 
SIR JOHN ISAAC THORNYCROPT, LL.D., F.R.S., was born in Home on the 1st February, 1843, in the Rua Sestina, which was then called the Rua Feliche, where his parents, Thomas and Mary Thornycroft, were living at the time. They were both distinguished sculptors, and from them he inherited a great deal of the talent which contributed to his success as an engineer.
His father was a keen amateur engineer, and from him he received his earliest instruction in mechanics and kindred subjects. There are still in existence the model locomotive which used to run around his studio, and which was large enough to ride upon, an 8-inch reflecting telescope, the speculum of which was as good as could be produced to-day, and a model boat fitted with a closed stokehold and forced draught, which is thought to be the first example of the system which has since been so generally adopted.
At an early date his father seems to have wished that he should adopt some sort of engineering as his profession and sent him to the Royal School of Naval Architecture and Marine Engineering at South Kensington, where he was for some time a contemporary student with the late Sir Philip Watts, M. Inst. C.E. While there he showed great aptitude and actually built a steam-launch in the studio of his father, who, at the time, was engaged on the Boadicea group which now stands at the corner of Westminster Bridge. The success of this launch seems to have decided his father that the designing and building of high speed boats should be the son’s work in life. He was sufficiently far-seeing to appreciate that, to be really successful, his son must first obtain a thorough scientific training, and as Glasgow University was at the time about the only place where applied science was taught, he decided that his son should go there; and, in due course, John Thornycroft obtained his diploma in engineering under the instruction of Lord Kelvin and Professor MacQuorn Rankine. Before going to Glasgow he served some time with Palmer’s Shipbuilding Company, Jarrow-on-Tyne, and so had some practical experience before the theoretical training which he subsequently received. After his course at the University he worked for some time in the drawing-office of Messrs. Randolph, Elder and Company, now the Fairfield Shipbuilding Company. Some of his first work was on the design of the Popofga circular ships which were being built for Russia, and he contributed a Paper to the Institution of Naval Architects in l869 referring to the work he had done in calculating their resistance. At this time his father bought some land at Chiswick with a view to his starting business as a builder of steam-launches, and Sir John soon turned out the “Miranda,” a steel launch of 58 HP., 45 feet 6 inches long, which gave a speed of 16.4 knots. She marked a definite step in the progress of small high-speed craft. As scepticism about the accuracy of the results had been expressed, he arranged with Sir Frederick Bramwell, Past-President, to make a trial and report. Sir Frederick confirmed the figures obtained. The “Miranda” was quickly followed by other fast launches which were built for service abroad as well as at home.
In 1872 his brother-in-law, Mr. John Donaldson, M. Inst. C.E., who had been his fellow student at Glasgow, joined him in partnership. The Whitehead torpedo had just been invented, and the naval authorities realized that, to make it an effective weapon, a high-speed launch was required to carry it. As a result of the successful speed results of his boats they were at once regarded as being suitable for the purpose, and in 1875 the British Admiralty placed with his firm an order for the “Lightning,” the first torpedo-boat of the British Navy. She was the first naval vessel to be fitted with the closed-stoke-hold system of forced draught which he had already applied to a number of launches that he had built. The “Lightning” was very similar to one of his earlier vessels, the “Gitana,” 80 feet in length, which had a speed of 18 knots. He was personally responsible for the details as well as the complete design of these early boats and their machinery, and the patent records show how many advances he made on the general practice at the time. He was a wonderfully neat draughtsman, and his line drawings were works of art. He could make freehand sketches of complicated details of mechanism which would piece together correctly without an assembly drawing.
The adoption of the torpedo-boat by the British and other navies greatly increased the activities and prosperity of his firm, Sir John devoting most of his attention to design and his partner to administration. He was the first to measure simultaneously the thrust power transmitted, and speed in experiments with screw propellers. As machinery was driven harder, the locomotive boiler which he applied to the early fast launches and torpedo-boats gave a good deal of trouble, and he soon recognized that it was unsuitable for the high degree of forcing which was necessary ; he therefore turned his attention to the possibility of employing boilers of the water-tube type. The boilers which he fitted at once showed their superiority over previous designs. The “Ariete,” a torpedo-boat built at Chiswick for Spain in 1887, held the record for speed at the time, developing more than 26 knots. In the face of considerable technical difficulties and the prejudices of many of his contemporaries, he strongly urged the adoption of a new type of boiler, and the British Admiralty eventually agreed to the "Speedy," a torpedo gun-boat of 810 tons, being fitted with them. She was the first British warship, of any size, to be fitted with water-tube boilers, and, as a result, developed about 4,500 HP. against 3,500 HP., the maximum that could be obtained with numerous other vessels of the class fitted with the older type. He contributed a Paper to The Institution giving the results of these early boiler experiments, having previously described the earlier types of torpedo-boats in a Paper "On Torpedo-Boats and Light Yachts for High Speed Steam Navigation," for which he was awarded a Watt Medal and a Telford Premium.
Improvements in the form of the hulls were constantly engaging his attention, and he was the first to adopt the flat form of stern which has since become general in small high-speed vessels. He took out patents for various improvements in screw propellers and the tunnel form of stern which has been so largely adopted for shallow-draught river vessels. With the adoption of the torpedo-boat destroyer by the British Navy, his firm supplied the first one fitted with water-tube boilers, namely the "Daring," and, at the same time, introduced the special design of four-cylinder triple-expansion engine which was balanced in an unusual way. The machinery of these destroyers was described in a Paper read before The Institution by Sir John and the late Mr. S. W. Barnaby, M. Inst. C.E., on "Torpedo-Boat Destroyers," for which the Authors each received a George Stephenson Medal and a Telford Premium. When the question arose of adopting the Parsons steam turbine for use in the Navy, he was appointed one of the two civilian members of Lord Fisher’s committee which recommended its adoption for the Dreadnought class of battleship and new destroyers. The “Tartar,” designed and built by his firm, was the only one of the oil-fired turbine destroyers to attain a speed of 37.5 knots. With the increase in the size of destroyers, the yard at Chiswick was not well placed, and the firm moved to more convenient premises at Woolston, Southampton, where numerous destroyers and other craft were built before the war period. Not only were numerous torpedo-boat destroyers supplied to governments all over the world, but vessels to the Thornycroft designs were built abroad and, with the general adoption of the water-tube boilers, the firm’s design was quickly taken up by Continental and American firms.
Sir John was never happy without some problem before him and at one time spent a great deal of labour designing and making apparatus to reduce the rolling of ships. He fitted a 300-ton yacht with a 6-ton moving weight controlled by hydraulic cylinders, which in turn were controlled by long- and short-period pendulums, and, as testified by the late Sir William White, this reduced the rolling by half. Of course, much work has since been done on the same subject, but his experiments were the first in which the matter was tackled in a scientific way. From his earliest days he had always looked forward to the possibility of building boats which would skim on the surface of the water and so avoid the ordinary wave-making resistance, and he took out patents at a very early date for skimming boats; but machinery in those days was not light enough. With the development of the light internal-combustion engine he saw the possibility of success ; he built a model-testing tank and experimented for several years in order to obtain the best form of hull. He built very successful boats as a result of these experiments. The single-step form of hull which he patented has since been generally adopted, not only for racing-boats, but also for seaplanes.
When the war came, the knowledge which his firm possessed enabled the small coastal motor torpedo-boats (known as “C.M.B.’s ”) to be produced with very successful results. So that he might devote any spare time to model experiments he built his experimental tank close to his house at Bembridge in the Isle of Wight. The tank is the same section as that of the National Physical Laboratory, but short. For the purpose for which he was working, namely the development of high-speed skimming boats, and with suitable electric arrangements which he devised for recording the speed and pull, it was found sufficient to run the model for a comparatively short distance. The form of hull which he evolved after several years’ work with models and actual boats has not been improved upon, and the boats built in different parts of the world, giving the highest speeds, have had a form of bow and steps almost identical with those of the models from which the coastal motor-boats were built. During the war period twenty-nine destroyers and flotilla leaders were built and more than 500 vessels were repaired by the firm.
During this period Sir John, assisted by his daughter Blanche, an Associate of the Institution of Naval Architects, did a considerable amount of work with his experimental tank and, among other things, established the resistance of the mooring-ropes of mines when inclined at different angles to the current. It is of some interest to record that towards the end of the war a proposal for a decoy-ship of shallow draught, able to pass over mines or torpedoes, was submitted to the Admiralty, and within an hour instructions were given that she was to be built and to take precedence over other construction. This vessel was 240 feet long and 35 feet beam, and it was no mean achievement that she was completed in 3 months. The success of the vessel was due to her shallow draught which was obtained by the employment of the tunnelled form of stern which Sir John patented many years ago, and which has since become universally adopted where very shallow draught is required with a screw vessel.
In more recent years his firm has become well known as builders of motor-vehicles as well as of ships, and it is interesting to record that there are, among his earliest drawings, designs for steam road vehicles and even a flying machine of the helicopter type.
He was elected an Associate of The Institution in 1873, and transferred to the class of Members in 1877. He served as a member of the Council from 1899 to 1907. In addition to contributing the Original Communications already referred to, he participated frequently in the discussions. He was an Honorary Vice-President of the Institution of Naval Architects, which he joined in 1869 ; and he was admitted to the Institution of Mechanical Engineers in 1876, subsequently being elected an Honorary Life Member. He was elected a Fellow of the Royal Society in 1893, and made an LL.D. of Glasgow in 1901. He was knighted in 1902.
He died at his residence, Steyne, Bembridge, on the 28th June, 1928.