Union-Jet. —Hollow-Top or Slit-Union. —Batswing.
Fig. 12.—Bray's "Special" Burners.
Mr. Bray's series of "special" burners—embracing union-jet, hollow-top, and batswing—are constructed upon the principle of, and in form are somewhat similar to Brönner's burners, which have already been fully described. Apart from its being of greater bulk, the main divergence in the construction of the "special" burner from that of the earlier "regulator" is the introduction, into the lower part of the brass case, of a plug or washer of enamel, pierced by a small circular hole for the admission of gas into the burner; the diameter of this hole determining the quantity of gas which, at any particular pressure, is admitted into the burner. Just above the enamel washer, a layer of muslin is inserted, as in the "regulator" burner; which, in this case, is for the purpose of subduing the agitation, or swirl, acquired by the current of gas in passing through the narrow aperture in the washer. A tip of enamel, made of the particular description (union-jet, hollow-top, or batswing) required, fitting into the upper part of the brass case, completes the burner. The objects aimed at in the "special" burner are to cause the gas to be consumed at the lowest pressure compatible with the maintenance of a firm flame, and with the least agitation, or swirl, in the current of gas as it issues from the burner. The former is attained, as in Brönner's burners, by diminishing the area of the opening admitting into the burner, without a corresponding diminution of the orifices through which the gas issues into the atmosphere; the latter, by the interposition of the layer of muslin which is immediately above the diminishing arrangement, as well as by the enlargement of the gas chamber in the upper part of the burner. The improvement thus effected in the illuminating power developed from the gas is well shown in the following tables extracted from an exhaustive series of tests of gas-burners carried out by Mr. T. Fairley, F.R.S.E., Borough Analyst of Leeds, and embodied by him in a report presented to the Leeds Corporation. The full text of the report will be found in the Journal of Gas Lighting for February 6, 1883.
Medium Lighting Power Union-Jets.
| "Regulator" Burners. | "Special" Burners. | ||||||||
| No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. | No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. |
| 3 | 0·5 | 3·50 | 6·8 | 9·7 | 3 | 0·5 | 3·43 | 11·3 | 16·4 |
| 3 | 1·0 | 4·80 | 6·9 | 7·2 | 3 | 1·0 | 4·90 | 15·6 | 15·8 |
| 3 | 1·5 | 6·20 | 7·5 | 6·05 | 3 | 1·5 | 6·03 | 17·6 | 14·6 |
| 4 | 0·5 | 4·65 | 12·2 | 13·1 | 4 | 0·5 | 3·73 | 13·3 | 17·8 |
| 4 | 1·0 | 6·67 | 14·2 | 10·6 | 4 | 1·0 | 5·15 | 17·4 | 16·9 |
| 4 | 1·5 | 8·16 | 14·2 | 8·8 | 4 | 1·5 | 6·57 | 22·4 | 17·1 |
| 5 | 0·5 | 5·72 | 17·0 | 14·9 | 5 | 0·5 | 4·80 | 17·6 | 18·3 |
| 5 | 1·0 | 7·97 | 20·0 | 12·6 | 5 | 1·0 | 6·67 | 24·4 | 18·3 |
| 5 | 1·5 | 9·73 | 21·8 | 11·2 | 5 | 1·5 | 8·30 | 30·0 | 18·2 |
| 6 | 0·5 | 5·90 | 18·0 | 15·2 | 6 | 0·5 | 5·48 | 20·1 | 18·3 |
| 6 | 1·0 | 8·35 | 23·0 | 13·8 | 6 | 1·0 | 7·65 | 28·4 | 18·6 |
| 6 | 1·5 | 10·60 | 28·0 | 13·2 | 6 | 1·5 | 9·20 | 34·2 | 18·7 |
Medium Lighting Power Slit-Unions.
| "Regulator" Burners. | "Special" Burners. | ||||||||
| No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. | No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. |
| 3 | 0·5 | 4·22 | 13·8 | 16·4 | 3 | 0·5 | 3·04 | 10·8 | 17·8 |
| 3 | 1·0 | 6·37 | 20·2 | 15·9 | 3 | 1·0 | 4·61 | 16·4 | 17·6 |
| 3 | 1·5 | 8·14 | 25·8 | 15·9 | 3 | 1·5 | 5·88 | 19·9 | 16·9 |
| 4 | 0·5 | 4·25 | 14·8 | 17·4 | 4 | 0·5 | 3·82 | 14·2 | 18·6 |
| 4 | 1·0 | 5·88 | 20·6 | 17·5 | 4 | 1·0 | 5·69 | 20·8 | 18·3 |
| 4 | 1·5 | 7·95 | 26·5 | 16·6 | 4 | 1·5 | 7·35 | 25·6 | 17·5 |
| 5 | 0·5 | 5·25 | 19·0 | 18·2 | 5 | 0·5 | 4·12 | 15·4 | 18·7 |
| 5 | 1·0 | 8·14 | 28·4 | 17·45 | 5 | 1·0 | 6·37 | 23·4 | 18·4 |
| 5 | 1·5 | 10·20 | 36·4 | 17·8 | 5 | 1·5 | 7·94 | 28·5 | 18·0 |
| 6 | 0·5 | 5·67 | 22·2 | 19·6 | 6 | 0·5 | 5·00 | 19·6 | 19·6 |
| 6 | 1·0 | 8·60 | 33·6 | 19·4 | 6 | 1·0 | 7·55 | 29·0 | 19·2 |
| 6 | 1·5 | 11·10 | 39·5 | 17·8 | 6 | 1·5 | 9·70 | 37·0 | 19·1 |
Medium Lighting Power Batswings.
| "Regulator" Burners. | "Special" Burners. | ||||||||
| No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. | No. of Burner | Pres- sure in Inches | Cubic Feet per Hour | Illumi- nating Power in Stand. Candls. | Illumi- Power per 5 Cubic Feet. |
| 3 | 0·5 | 4·16 | 12·6 | 15·1 | 3 | 0·5 | 3·37 | 12·4 | 18·4 |
| 3 | 1·0 | 5·64 | 16·6 | 14·8 | 3 | 1·0 | 5·25 | 20·4 | 19·4 |
| 3 | 1·5 | 7·83 | 21·0 | 13·4 | 3 | 1·5 | 7·13 | 24·0 | 16·8 |
| 4 | 0·5 | 4·26 | 14·0 | 16·4 | 4 | 0·5 | 3·67 | 13·0 | 17·7 |
| 4 | 1·0 | 6·74 | 21·2 | 15·6 | 4 | 1·0 | 5·55 | 20·6 | 18·6 |
| 4 | 1·5 | 7·81 | 24·0 | 15·3 | 4 | 1·5 | 7·13 | 26·0 | 18·2 |
| 5 | 0·5 | 4·76 | 15·4 | 16·2 | 5 | 0·5 | 3·86 | 14·6 | 18·9 |
| 5 | 1·0 | 6·93 | 20·4 | 14·7 | 5 | 1·0 | 5·85 | 22·6 | 19·4 |
| 5 | 1·5 | 8·72 | 25·8 | 14·7 | 5 | 1·5 | 7·53 | 28·0 | 18·6 |
| 6 | 0·5 | 6·04 | 20·0 | 16·5 | 6 | 0·5 | 4·86 | 19·4 | 20·0 |
| 6 | 1·0 | 8·82 | 29·4 | 16·6 | 6 | 1·0 | 7·53 | 31·6 | 21·0 |
| 6 | 1·5 | 11·10 | 31·6 | 14·2 | 6 | 1·5 | 9·60 | 39·0 | 20·4 |
The quality of the gas operated upon averaged about 19 candles when tested with the Standard London Argand Burner.
In a former part of this treatise it was remarked that the flames produced by the modern representatives[ [10] of the batswing and fishtail burners have lost the original resemblance to the objects whence the names of those burners were derived; and that the two flames have gradually approached each other in shape, until, in their latest developments, they are practically identical. We have seen how that, by the invention of the hollow-top, a burner is obtained apparently, to all outward appearance, the same as the batswing, yet giving a greatly improved form of flame. We have now to learn how the fishtail, or union-jet burner has been modified so as to yield a flame closely agreeing with that produced by the improved slit burner.