Part 3 (1/2)

Nos 1 and 2 were found to be faulty in bothsurfaces placed directly over the fire, as it cracked as soon as any scale forht-iron tubes were substituted for the cast-iron heating tubes, the ends being brightened, laid in moulds, and the headers cast on

The stean were insufficient to secure regularity of action, there being no reserve upon which to draw during firing or when the water was fed inter it in the nest of tubes for the steam space was found to be impracticable The stea to the rate at which it was being drawn froe in the lowermost point of the boiler at the rear end and the exposed portions cracked off at this point when subjected to the furnace heat

[Illustration: No 4]

No 4 A plain cylinder, carrying the water line at its center and leaving the upper half for stea the steam and water space in Nos 1, 2 and 3 The sections were made as in No 3 and a mud drum added to the rear end of the sections at the point that was lowest and farthest reases were made to pass off at one side and did not come into contact with the h the increase of separating surface and steae for heat to tide over irregularities of firing and feeding By the addition of the drun, retaining all of the features of safety As the drum was removed from the direct action of the fire, it was not subjected to excessive strain due to unequal expansion, and its diae in comparison with that of the tubes formerly used, was small when compared with that of cylindrical boilers Difficulties were encountered in this boiler in securing reliable joints between the wrought-iron tubes and the cast-iron headers

[Illustration: No 5]

No 5 In this design, wrought-iron water legs were substituted for the cast-iron headers, the tubes being expanded into the inside sheets and a large cover placed opposite the front end of the tubes for cleaning The tubes were staggered one above the other, an arrangement found to be more efficient in the absorption of heat than where they were placed in vertical rows In other respects, the boiler was similar to No 4, except that it had lost the ih the introduction of the very objectionable feature of flat stayed surfaces

The large doors for access to the tubes were also a cause of weakness

An installation of these boilers was ar Refinery in Baltimore, and while they were satisfactory in their operation, were never duplicated

[Illustration: No 6]

No 6 This was a er tubes were used and over which the gases were caused to make three passes with a view of better economy In addition, some of the stayed surfaces were oe access doors A nun were built but their excessive first cost, the lack of adjustability of the structure under varying temperatures, and the inconvenience of transportation, led to No 7

[Illustration: No 7]

No 7 In this boiler, the headers and water legs were replaced by T-heads screwed to the ends of the inclined tubes The faces of these Ts were milled and the tubes placed one above the other with the h each vertical section of the T-heads and through connecting boxes on the heads of the drue nun were built and many were in successful operation for over twenty years

In most instances, however, they were altered to later types

[Illustration: No 8]

[Illustration: No 9]

Nos 8 and 9 These boilers were known as the Griffith & Wundrued in The Babcock & Wilcox Co Experiases across the tubes and the doard circulation of the water at the rear of the boiler was carried to the bottom row of tubes In No 9 an attempt wasthe ales to the line of tubes was used but as there was no provision made to secure dry steam, the results were not satisfactory The next move in the direction of safety was the ele drum

[Illustration: No 10]

This is shown in No 10 A nest of small horizontal drule druer diameter A set of circulation tubes was placed at an inter tubes and the horizontal dru the steam reservoir These circulators were to return to the rear end of the circulating tubes the water carried up by the circulation, and in this ere to allow only steam to be delivered to the small drums above

There was no improvement in the action of this boiler over that of No

9

The four passages of the gas over the tubes tried in Nos 8, 9 and 10 were not found to add to the economy of the boiler

[Illustration: No 11]

No 11 A trial was next made of a box coil system, in which the water wasdelivered to the drum above The tendency here, as in all similar boilers, was to form steam in thethe tubes practically dry until the steam found an outlet and the water returned This boiler had, in addition to a defective circulation, a decidedly geyser-like action and produced wet steam