Another study described by Dr. Wallin was made by Heilman in 1907 of 1000 Camden repeaters. The correlation between pedagogical retardation and percentage of defect in each group was as follows: Defects Retardation 1 yr. 2 yr. 3 yr. 4 yr. 5 yr. Per Cent Health 16.5 21.3 28.0 19.0 37.5 Nutrition 13.4 8.9 17.2 20.2 17.5 _Adenoids_ _6.2_ _7.3_ _8.1_ _9.6_ _7.5_ Speech 5.2 5.1 4.2 10.5 20.0 Visual defects 15.5 15.9 18.2 22.8 22.8 Auditory 8.2 6.7 4.9 6.1 10.0 Burpitt[9] describes an investigation of 400 children, 200 male and 200 female, considered by their teachers to be "dull and backward, but not to fall within the meaning of feeble-mindedness as given in the Mental Deficiency Act of 1913." The children were examined for physical defects and other abnormal conditions. The author says that in 36 per cent of the cases, the cause for backwardness was found to be "inherent dullness." (The basis for judgment of inherent dullness is not given.) Adenoids and tonsillar tissue were found in 18.75 per cent of the cases, and were "more prevalent than among the children of the area as a whole." [9]: H. R. Burpitt. Relative Degrees of Dullness and Backwardness in School Children and their Causation. Journal of Mental Science, 1916. The degree of retardation, based upon the number of school standards below normal, was ascertained for pupils who suffered from various defects. The relative retardation was expressed by the fraction n/(A-5) where n = number of years retarded, and A = age. Eighteen per cent of the children were so retarded that the fraction was greater than 3-9. These were divided into two groups,--3-9 to 4-9 and 4-9 to 5-9. The results are given in the following table: Causes 46 children 24 children 3-9 to 4-9 4-9 to 5-9 Inherent dullness only 8 3 Inherent dullness and one or more physical defects 7 2 Irregular attendance with one or more physical defects 9 6 Irregular attendance 2 3 _Adenoids only_ _2_ _0_ Turning to what the author calls single causes,--present in 170 cases out of the 400,-- Causes 151 children 19 children 1-9 to 3-9 3-9 to 6-9 Irregular attendance 51 6 _Adenoids_ _24_ _2_ Inherent dullness 59 11